25 Jan
2014
25 Jan
'14
10:30 p.m.
Message: 6
Date: Sun, 19 Jan 2014 14:39:21 -0800
From: Chuck Guzis <cclist at sydex.com>
To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
Subject: Re: 1541 Alignment disk
Message-ID: <52DC5419.7020309 at sydex.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 01/19/2014 12:45 PM, geneb wrote:
Ok, which disk would I purchase then?
I'm pretty sure Dan is after an analog
alignment disk. There was a
vendor mentioned here a couple of weeks ago, but I don't recall their name.
Accurite:
http://www.accurite.com/AAD.html
--Chuck 
25 Jan
25 Jan
11:04 p.m.
On 01/25/2014 07:30 PM, Daniel V. Mackey wrote:
Ok, which disk would I purchase then?
I'd first check with Accurite, but 208-40 seems to be a fair match. The
1541 is SS, 48 tpi, IIRC. The 1571 is double-sided.
It helps if your 'scope has a fairly long persistence phosphor, or is a
DSO or you have been skimping on your vitamin A. 300 RPM is only 5
revolutions per second, after all.
--Chuck
26 Jan
26 Jan
1:08 p.m.
On 01/25/2014 07:30 PM, Daniel V. Mackey wrote:
Assuming you can get one with the right specifications, I would always
bey a double-sided alignment disk. You may need it later for DS drives.
However, in 99% of floppy drives you cannot (officially) adjust the heads
sparately. You align one side, check the other, if the latter is not
aligned properly yuo have to repalce the head assembly. So a single-sided
alignment disk is perhaps not a mjor problem,
Ok, which disk would I purchase then?
I'd first check with Accurite, but 208-40 seems to be a fair match. The
1541 is SS, 48 tpi, IIRC. The 1571 is double-sided.
It helps if your 'scope has a fairly long persistence phosphor, or is a
DSO or you have been skimping on your vitamin A. 300 RPM is only 5
revolutions per second, after all.
At one time there was a rather nice disk alignemtn device for PCs. It
wouldn't allas work wit ha 1541, but it worked with most standard dirves.
It consisted of a box containing a microcontroller (8048 IIRC) and am
ADC. this connected to the PC's serial port. You conencted the
drive-under-test to the PC is B: and ran the suppleid software. This
would run on _anything_ (I think the minimum spec was 256K RAM and one
serial port).
You then sleected thge drive type from a menu and it displayed an outline
oif the PCB using the IBM line drawing characters (yes, it would run on
an MDA display). It showed you where to connect half-a-dozen wirtes from
the inteface box to the drive PCB., Then put a catseye disk i nthe drive,
select the apropraite pattern, and it displaed the catseyes on the PC
screen (again using extanded 'text' characters!) and told you how far out
of alignment is was and which way.
I've it several times, and for the drives it supports it's a lot easier
than usign a 'scope.. I think it was called soemthing like 'Microtest',
the proble, of course, is finding it.
-tony
9:14 p.m.
New subject: Antic episode 7 now out!
Episode #7 of The Antic Podcast now out! News, tips, guest host Paul Nurminen from
Intellivisionaries podcast, & basics of Atari disks!
Ataripodcast.com or iTunes
On Jan 26, 2014, at 1:08 PM, ard at p850ug1.demon.co.uk (Tony Duell) wrote:
Assuming you can get one with the right specifications, I would always
bey a double-sided alignment disk. You may need it later for DS drives.
However, in 99% of floppy drives you cannot (officially) adjust the heads
sparately. You align one side, check the other, if the latter is not
aligned properly yuo have to repalce the head assembly. So a single-sided
alignment disk is perhaps not a mjor problem,
On 01/25/2014 07:30 PM, Daniel V. Mackey wrote:
Ok, which disk would I purchase then?
I'd first check with Accurite, but 208-40 seems to be a fair match. The
1541 is SS, 48 tpi, IIRC. The 1571 is double-sided.
It helps if your 'scope has a fairly long persistence phosphor, or is a
DSO or you have been skimping on your vitamin A. 300 RPM is only 5
revolutions per second, after all.
At one time there was a rather nice disk alignemtn device for PCs. It
wouldn't allas work wit ha 1541, but it worked with most standard dirves.
It consisted of a box containing a microcontroller (8048 IIRC) and am
ADC. this connected to the PC's serial port. You conencted the
drive-under-test to the PC is B: and ran the suppleid software. This
would run on _anything_ (I think the minimum spec was 256K RAM and one
serial port).
You then sleected thge drive type from a menu and it displayed an outline
oif the PCB using the IBM line drawing characters (yes, it would run on
an MDA display). It showed you where to connect half-a-dozen wirtes from
the inteface box to the drive PCB., Then put a catseye disk i nthe drive,
select the apropraite pattern, and it displaed the catseyes on the PC
screen (again using extanded 'text' characters!) and told you how far out
of alignment is was and which way.
I've it several times, and for the drives it supports it's a lot easier
than usign a 'scope.. I think it was called soemthing like 'Microtest',
the proble, of course, is finding it.
-tony 
11:44 p.m.
New subject: Antic episode 7 now out!
On Jan 26, 2014, at 18:14 , Randall.kindig <randall.kindig at gmail.com> wrote:
Episode #7 of The Antic Podcast now out! News, tips,
guest host Paul Nurminen from Intellivisionaries podcast, & basics of Atari disks!
Good episode! Is it available on LP record? :)
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
27 Jan
27 Jan
midnight
New subject: Antic episode 7 now out!
On 01/26/2014 08:44 PM, Mark J. Blair wrote:
On Jan 26, 2014, at 18:14 , Randall.kindig <randall.kindig at gmail.com> wrote:
They're working on it--currently only on wax cylinder..
Episode #7 of The Antic Podcast now out! News,
tips, guest host Paul Nurminen from Intellivisionaries podcast, & basics of Atari
disks!
Good episode! Is it available on LP record? :)
12:16 a.m.
New subject: Antic episode 7 now out!
On Jan 26, 2014, at 21:00 , Chuck Guzis <cclist at sydex.com> wrote:
They're working on it--currently only on wax
cylinder..
A friend of mine might be interested in that for his Ediphone... :)
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
8:11 a.m.
New subject: Antic episode 7 now out!
Funny! We should do that, but it would take several records. How many want to buy in?
:)
Randy
Sent from my iPhone
On Jan 26, 2014, at 11:44 PM, "Mark J.
Blair" <nf6x at nf6x.net> wrote:
On Jan 26, 2014, at 18:14 , Randall.kindig
<randall.kindig at gmail.com> wrote:
Episode #7 of The Antic Podcast now out! News, tips, guest host Paul Nurminen from
Intellivisionaries podcast, & basics of Atari disks!
Good episode! Is it available on LP record? :)
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
9:45 a.m.
New subject: Antic episode 7 now out!
On 27 January 2014 02:14, Randall.kindig <randall.kindig at gmail.com> wrote:
Episode #7 of The Antic Podcast now out! News, tips,
guest host Paul Nurminen from Intellivisionaries podcast, & basics of Atari disks!
Ataripodcast.com or iTunes
Who are you hijacking someone else's thread to top-post your spam?
Do you actively want people to hate and ignore you? Because it's
working over here.
--
Liam Proven ? Profile: http://lproven.livejournal.com/profile
Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven
MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven
Tel: +44 20-8685-0498 ? Cell: +44 7939-087884
10 a.m.
New subject: Antic episode 7 now out!
On Jan 27, 2014, at 06:45 , Liam Proven <lproven at gmail.com> wrote:
Who are you hijacking someone else's thread to
top-post your spam?
Randall, if you reply to a message rather than creating a new one from scratch, many email
clients will associate your message with the thread you replied to even if you change the
subject line. It's much better to start a new topic with a new message, not a reply to
an old one.
Do you actively want people to hate and ignore you?
Because it's
working over here.
Someone has a case of the Mondays! :)
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
12:11 p.m.
New subject: Antic episode 7 now out!
On 27 January 2014 15:27, BE Arnold <bearnold at outlook.com> wrote:
No, I'm this much of a grumpy bugger every day!
--
Liam Proven ? Profile: http://lproven.livejournal.com/profile
Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven
MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven
Tel: +44 20-8685-0498 ? Cell: +44 7939-087884
Someone has a
case of the Mondays! :)
Yeah, applies here also I think.
10:40 a.m.
New subject: Antic episode 7 now out!
I apologize. It was inadvertent. I will do it correctly next time.
Randy
Sent from my iPhone
On Jan 27, 2014, at 10:00 AM, "Mark J.
Blair" <nf6x at nf6x.net> wrote:
On Jan 27, 2014, at 06:45 , Liam Proven
<lproven at gmail.com> wrote:
Who are you hijacking someone else's thread to top-post your spam?
Randall, if you reply to a message rather than creating a new one from scratch, many
email clients will associate your message with the thread you replied to even if you
change the subject line. It's much better to start a new topic with a new message, not
a reply to an old one.
Do you actively want people to hate and ignore
you? Because it's
working over here.
Someone has a case of the Mondays! :)
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
10:01 a.m.
New subject: Antic episode 7 now out!
On Jan 27, 2014, at 9:50 AM, "Liam Proven"
<lproven at gmail.com> wrote:
Isn't thread mixing a relatively common problem with the cct mail server?
I tend to see it often.
On 27 January 2014 02:14, Randall.kindig
<randall.kindig at gmail.com> wrote:
Episode #7 of The Antic Podcast now out! News, tips, guest host Paul Nurminen from
Intellivisionaries podcast, & basics of Atari disks!
Ataripodcast.com or iTunes
Who are you hijacking someone else's thread to top-post
I guess I'm too young and
inexperienced to understand why this pains you that much.
Hmm, that could be read as flame-bait, which it truly is not.
I can understand why you don't like it, but the anger is what I don't get.
10:44 a.m.
New subject: Antic episode 7 now out!
On 27 January 2014 15:01, BE Arnold <bearnold at outlook.com> wrote:
I can understand why you don't like it, but the
anger is what I don't get.
I find top-posted threads unreadable. It means that there are a
shrinking number of small corners of the Internet where I can actually
read and participate in conversations.
If someone appears in one of those corners and top-posts everywhere,
they badge themselves as a clueless newbie who couldn't be bothered to
go to the minimal effort of learning how things work and how to
participate. This person is therefore very unlikely to be a useful
member of that community; in fact, they're more likely to worsen the
signal:noise ratio and thus contribute to its decline.
Yeah, I'm a grumpy old git, at 46. I don't feel old inside, but my
body does. I don't like getting, but it's better than the alternative.
But one can't not get old, except by dying, so one might as well
embrace it. So, yeah, grumpy old curmudgeon. Yay. Perhaps I'll get to
take over Grumpy Ol' Fred's crown or something.
--
Liam Proven ? Profile: http://lproven.livejournal.com/profile
Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven
MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven
Tel: +44 20-8685-0498 ? Cell: +44 7939-087884
11:50 a.m.
New subject: Antic episode 7 now out!
> Who are you hijacking someone else's thread
On Mon, 27 Jan 2014, BE Arnold wrote:
Isn't thread mixing a relatively common problem
with the cct mail server?
I tend to see it often.
. . . because, in THIS case, he did not trim off the message that he was
replying to, which was about a completely orthogonal subject.
The "in reply to" linking done by some mail clients was a significantly
lesser issue.
I was confused, trying to understand the connection between alignment
disks and an Atari Podcast. (about aligning Atari drives??)
--
Grumpy Ol' Fred cisin at xenosoft.com
http://www.xenosoft.com/FPUIB
to top-post
I guess I'm too young and
inexperienced to understand why this pains you that much.
Hmm, that could be read as flame-bait, which it truly is not.
I can understand why you don't like it, but the anger is what I don't get.
12:18 p.m.
New subject: Antic episode 7 now out!
to top-post
I guess I'm too young and inexperienced to understand why this pains
you that much. 
25 Jan
25 Jan
11:56 p.m.
(Chiming in..)
I might need one of these as well.
And here's a question for the experts: Why would one actually need a "1541
specific" alignment disk - wouldn't there be a generic alignment disk,
which would be suitable to all drives which use the same track (and not
necessarily even sector) geometry?
Isn't the alignment disc essentially a series of concentric analog
sine-wave audio tracks, with each audio track recorded on the centerline of
a disc data track?
It would seem that so long as the drive uses the same track spacing, one
disc could serve many mechanisms. Please correct me on that, if needed.
On Sat, Jan 25, 2014 at 9:30 PM, Daniel V. Mackey <n2dvm at arrl.net> wrote:
Message: 6
Date: Sun, 19 Jan 2014 14:39:21 -0800
From: Chuck Guzis <cclist at sydex.com>
To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
Subject: Re: 1541 Alignment disk
Message-ID: <52DC5419.7020309 at sydex.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 01/19/2014 12:45 PM, geneb wrote:
Ok, which disk would I purchase then?
I'm pretty sure Dan is after an analog
alignment disk. There was a
vendor mentioned here a couple of weeks ago, but I don't recall their
name.
Accurite:
http://www.accurite.com/AAD.html
--Chuck
26 Jan
26 Jan
12:01 a.m.
Heh, I may have just answered my own question.
I clicked the link (above) to Accurite, and from what I garner I was
essentially correct - there are "generic" discs which might cover many
mechanisms, but track spacing & count aren't the only relevant parameter.
Am I getting that right? =)
On Sat, Jan 25, 2014 at 10:56 PM, drlegendre . <drlegendre at gmail.com> wrote:
(Chiming in..)
I might need one of these as well.
And here's a question for the experts: Why would one actually need a "1541
specific" alignment disk - wouldn't there be a generic alignment disk,
which would be suitable to all drives which use the same track (and not
necessarily even sector) geometry?
Isn't the alignment disc essentially a series of concentric analog
sine-wave audio tracks, with each audio track recorded on the centerline of
a disc data track?
It would seem that so long as the drive uses the same track spacing, one
disc could serve many mechanisms. Please correct me on that, if needed.
On Sat, Jan 25, 2014 at 9:30 PM, Daniel V. Mackey <n2dvm at arrl.net> wrote:
Message: 6
Date: Sun, 19 Jan 2014 14:39:21 -0800
From: Chuck Guzis <cclist at sydex.com>
To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
Subject: Re: 1541 Alignment disk
Message-ID: <52DC5419.7020309 at sydex.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 01/19/2014 12:45 PM, geneb wrote:
Ok, which disk would I purchase then?
I'm pretty sure Dan is after an analog
alignment disk. There was a
vendor mentioned here a couple of weeks ago, but I don't recall their
name.
Accurite:
http://www.accurite.com/AAD.html
--Chuck
1:03 p.m.
On 01/25/2014 09:01 PM, drlegendre . wrote:
Heh, I may have just answered my own question.
I clicked the link (above) to Accurite, and from what I garner I was
essentially correct - there are "generic" discs which might cover many
mechanisms, but track spacing & count aren't the only relevant parameter.
Am I getting that right? =)
Yes, your 'scope test point is essentially the output of the read
amplifier; hence, the term "analog" alignment diskette.
--Chuck
1:17 p.m.
I have an official 1541 alignment disk.
I forget which one it is, but it's an original disk.
It has software on the disk you run as well,
I think it was freedom-1541 or something.
I think I asked years ago about duplicating these,
but is there a practical way to do that with just a 1541?
I mean, if you align a drive using a scope with the disk,
then duplicate it, how reliable is that copy for alignment of other drives?
Dan.
Date: Sun, 26 Jan 2014 10:03:06 -0800
From: cclist at sydex.com
To:
Subject: Re: 1541 Alignment disk
On 01/25/2014 09:01 PM, drlegendre . wrote:
Heh, I may have just answered my own question.
I clicked the link (above) to Accurite, and from what I garner I was
essentially correct - there are "generic" discs which might cover many
mechanisms, but track spacing & count aren't the only relevant parameter.
Am I getting that right? =)
Yes, your 'scope test point is essentially the output of the read
amplifier; hence, the term "analog" alignment diskette.
--Chuck
1:37 p.m.
I think I asked years ago about duplicating these,
but is there a practical way to do that with just a 1541?
I doubt it.
Most 'digitial alignemnt disks' -- the ones that don't need a 'scope --
have sectors delibrately recorded to oenar or too far from the spindle --
that is 'misaligned'. By seeing which ones are readable, the software can
determine if the heads re too near or too far from the spindle (if more
secectors too far fro mteh spindel are readable than ones too near the
spindle, the headad are also too far from the spindle).
Needl;ess to say you can't copy such a disk with a stnadard drivem no
matter how well aligned it is.
-tony
4:08 p.m.
> I think I asked years ago about duplicating
these,
> but is there a practical way to do that with just a 1541?
On Sun, 26 Jan 2014, Tony Duell wrote:
Needl;ess to say you can't copy such a disk with a
stnadard drivem no
matter how well aligned it is.
Ah, but if you DID succeed in copying it with a standard drive,
(and it really WAS duplicated, not just copying sectors into their
correct positions), then it would prove that the drive was seriously
out of alignment in strange ways. SOME sequences of sectors MIGHT
permit it to copy if the hub ws off center.
2:22 p.m.
I think I asked years ago about duplicating these,
but is there a practical way to do that with just a 1541?
NO!
NO!
NO!
What you can get PRODUCED by a normal drive, is a NORMAL disk.
What you can get PRODUCED by a normal drive, is a NORMAL disk.
What you can get PRODUCED by a normal drive, is a NORMAL disk.
You CAN NOT produce an alignment disk using a normal drive with a normal
controller.
You CAN NOT produce an alignment disk using a normal drive with a normal
controller.
You CAN NOT produce an alignment disk using a normal drive with a normal
controller.
I mean, if you align a drive using a scope with the
disk,
then duplicate it, how reliable is that copy for alignment of other drives?
WORTHLESS.
What you create with the normal controller with normal drive is a NORMAL
disk. IT IS ABSOLUTELY NOT AN ALIGNMENT DISK!
A "digital alignment disk" is a disk produced using a special drive, that
DELIBERATELY has sectors written OUT OF ALIGNMENT, in order to see which
sectors (HOW FAR OUT OF ALIGNMENT, AND IN WHICH DIRECTION) can be read by
the drive. Doing so provides a "reasonable" level of measurement of how
far out of alignment the drive is, and which direction. A disk written
with a NORMAL drive is aligned for that drive, and can NOT check anything
except whether a given drive is close enbough to alignment with the drive
that created that disk to be able to reade it. People who think that
THAT is "correct alignment" really don't give a shit whether the drive is
accurately aligned, or where within the range that succeeds in reading
THAT disk it might be. It is "close enough" to be able to read/recover
disks written by that drive; it is NOT acceptable for writing disks,
particularly for distribution, or even exchanging with other people who
have been doing the same, and have drives ELSEWHERE in the range that
reads THEIR "known good" disk.
It is a BAD, STUPID IDEA!
If you take a yardstick, and use it to make marks on a stick, and then use
that stick to make marks on another stick, and continue to use each stick
to make the marks on the next stick, HOW MANY sticks can you make that you
would claim are accurate?
Disunirregardless of the alignment of the drive, ANY disks created by that
drive are aligned to that drive - they are ABSOLUTELY NOT a graduated
and calibrated series of misalignments - they are ALL aligned to that
drive. Yes, "piracy" programs (blow it out your ass if that offends you),
can make a "copy" of the disk. But THAT "copy" is aligned to that
drive,
it is NOT an alignment disk, and is absolutely totally useless for
checking alignment of anything.
An "analog" alignment disk can not be created with a "normal"
controller/drive combination. Instead of "normal" digital data/sectors,
it has SPECIAL tracks written by special hardware. They are analog tracks,
containing signals for testing drives, and a normal drive/controller can
read them, but can NOT write them.
So, anybody who claims to "duplicate" an alignment disk with stock
hardware, disunirregardless of what software is used, is an ignorant
asshole.
3:14 p.m.
On 01/26/2014 11:22 AM, Fred Cisin wrote:
So, anybody who claims to "duplicate" an
alignment disk with stock
hardware, disunirregardless of what software is used, is an ignorant
asshole.
Well, I don't claim to be able to duplicate a digital alignment disk,
but I think one could be fabricated with a slightly modified "ordinary"
drive in good condition.
As an analogy, suppose one has a 1% tolerance carbon composition
reference resistor. It's certainly possible to come up with another 1%
tolerance resistor by selecting from a mixed batch of 20% resistors,
assuming the the closer tolerance components haven't been selected out
by the vendor.
In a similar manner, I think that if a drive can be slightly modified so
that the hub clamp has a slight eccentricity (with respect to the
spindle), a pattern would result upon writing that centered around the
ideal track location, but would also vary a bit outside and inside with
respect to it. (Picture a 45 RPM audio record being played on a
standard turntable without an adapter. The result would be a playback
with a lot of "wow", but at some point, would be the correct pitch.
Sort of like a broken clock being accurate twice a day.
At any rate, given such a disk, one would only need to identify the
position and address marks closest to the ideal position and note that.
When inserted into an ordinary drive, one could simply sample address
headers and determine that the particular address mark lay in the center
of a cluster of readable address marks.
Not lab-grade alignment, but surely something that could be useful.
I haven't tried this myself, but I see no reason why it shouldn't work.
And I don't think that I'm an ignorant asshole.
--Chuck
3:53 p.m.
In a similar manner, I think that if a drive can be
slightly modified so
that the hub clamp has a slight eccentricity (with respect to the
spindle), a pattern would result upon writing that centered around the
Sure, that;s essentaily the pattern on n analogue alignment disk.
I think machining the drive hub to give the rigth degree of sccentricity
would be non-trivial.
I did wonder if you could modify the positioner circuitry. Most floppy
drives use stepper motors, and as is well-know, if you feed carefully
controleld currents into the windings you can 'micro step' them, you can
get them to settle between their normal positions. I wonder if you could
feed sutiable signals in to wobble the headjust enoguh (synchronised wit
hthe spindle rotation) to write the eccntric track.
-tony
4:31 p.m.
On Jan 26, 2014, at 3:53 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Not with a milling machine and a boring head. Or perhaps even a lathe with a 4-jaw chuck
and careful checking with a dial indicator.
paul
In a similar
manner, I think that if a drive can be slightly modified so
that the hub clamp has a slight eccentricity (with respect to the
spindle), a pattern would result upon writing that centered around the
Sure, that;s essentaily the pattern on n analogue alignment disk.
I think machining the drive hub to give the rigth degree of sccentricity
would be non-trivial.
27 Jan
27 Jan
3:01 p.m.
I think
machining the drive hub to give the right degree of sccentricity
would be non-trivial.
Not with a milling machine and a boring head. Or perhaps even a lathe
with a 4-jaw chuck and careful checking with a dial indicator.
26 Jan
26 Jan
6:18 p.m.
On 01/26/2014 12:53 PM, Tony Duell wrote:
I think machining the drive hub to give the rigth
degree of sccentricity
would be non-trivial.
Were I do go about this, I'd probably start by gluing a thin shim (a few
mills) into the cup of a Shugart-style clamp arrangement. Most drives
still use this. The "cone" has flexible fingers, so it should matter
for thin shims. Failing that, you'd probably have to separate the cup
from the spindle and tinker some with the shaft hole.
I did wonder if you could modify the positioner
circuitry. Most floppy
drives use stepper motors, and as is well-know, if you feed carefully
controleld currents into the windings you can 'micro step' them, you can
get them to settle between their normal positions. I wonder if you could
feed sutiable signals in to wobble the headjust enoguh (synchronised wit
hthe spindle rotation) to write the eccntric track.
In the case of 5.25" "megafloppy" drives, such as the Drivetek, that
would be almost trivial, once you got into the drive MCU firmware That
is, if the "fine" stepper could move quickly enough.
--Chuck
27 Jan
27 Jan
11:35 a.m.
Many of the analog ones were made with two
tones. One would be 1 cycle off per revolution.
The space between the two tones would be the center
of the tracks.
No need to make an eccentric spindle.
If you want to make an eccentric, it is easy
if you saw the end off and make a center hole
slightly large and connect it back tot he spindle
with a screw.
Dwight
----------------------------------------
Date: Sun, 26 Jan 2014 15:18:18 -0800
From: cclist at sydex.com
To:
Subject: Re: 1541 Alignment disk
On 01/26/2014 12:53 PM, Tony Duell wrote:
I think machining the drive hub to give the rigth
degree of sccentricity
would be non-trivial.
Were I do go about this, I'd probably start by gluing a thin shim (a few
mills) into the cup of a Shugart-style clamp arrangement. Most drives
still use this. The "cone" has flexible fingers, so it should matter
for thin shims. Failing that, you'd probably have to separate the cup
from the spindle and tinker some with the shaft hole.
I did wonder if you could modify the positioner
circuitry. Most floppy
drives use stepper motors, and as is well-know, if you feed carefully
controleld currents into the windings you can 'micro step' them, you can
get them to settle between their normal positions. I wonder if you could
feed sutiable signals in to wobble the headjust enoguh (synchronised wit
hthe spindle rotation) to write the eccntric track.
In the case of 5.25" "megafloppy" drives, such as the Drivetek, that
would be almost trivial, once you got into the drive MCU firmware That
is, if the "fine" stepper could move quickly enough.
--Chuck
2:33 p.m.
On 01/27/2014 08:35 AM, dwight wrote:
Many of the analog ones were made with two
tones. One would be 1 cycle off per revolution.
The space between the two tones would be the center
of the tracks.
That would be with very special equipment. Don't most ordinary floppy
heads feature tunnel erase?
No need to make an eccentric spindle.
If you want to make an eccentric, it is easy
if you saw the end off and make a center hole
slightly large and connect it back tot he spindle
with a screw.
I suspect something a lot more simple could be done. Consider that a
radial alignment of +/- 1 mil is considered to be "good enough" and that
the thickness of a piece of 20 lb. letter paper is 9 mils. One might
even give the spindle a couple of lateral taps with a small hammer to
achieve that level of eccentricity.
--Chuck
6:14 p.m.
On Mon, 27 Jan 2014, Chuck Guzis wrote:
I suspect something a lot more simple could be done.
Consider that a
radial alignment of +/- 1 mil is considered to be "good enough" and that
the thickness of a piece of 20 lb. letter paper is 9 mils. One might
even give the spindle a couple of lateral taps with a small hammer to
achieve that level of eccentricity.
But certainly not USPS level of re-alignment!
7:38 p.m.
On 01/27/2014 03:14 PM, Fred Cisin wrote:
On Mon, 27 Jan 2014, Chuck Guzis wrote:
No, but the USPS charges more (and more..)
--Chuck
I suspect something a lot more simple could be
done. Consider that a
radial alignment of +/- 1 mil is considered to be "good enough" and that
the thickness of a piece of 20 lb. letter paper is 9 mils. One might
even give the spindle a couple of lateral taps with a small hammer to
achieve that level of eccentricity.
But certainly not USPS level of re-alignment!
9:41 p.m.
From: cclist at sydex.com
On 01/27/2014 08:35 AM, dwight wrote:
I don't think disconnecting a wire going to
the head is particularly special.
This is only there to remove cross talk. For the
analog signal, we want cross talk.
Dwight
Many of the analog ones were made with two
tones. One would be 1 cycle off per revolution.
The space between the two tones would be the center
of the tracks.
That would be with very special equipment. Don't most ordinary floppy
heads feature tunnel erase?
--Chuck
3:20 p.m.
In the case of 5.25" "megafloppy"
drives, such as the Drivetek, that
would be almost trivial, once you got into the drive MCU firmware That
Err, yes... That's a big 'onece you get' :-)
is, if the "fine" stepper could move quickly
enough.
I was thinking of the normal stepper-motor posiitoend drives. Many of tha
later onescould step betwene tracks in 6ms. Given tha thr disk takes
200ms to rotate once, it would appaer you proably could wobble the head
fast enough.
Most of the time 2 stpper widnigns are driven on each track. I would
think if you varied the current i nthe 2 windings it was no logner
equaly, the head would be displaced slightly. Wobble siad currents nad
you might be able to ghet the head to do what you need.
-tony
26 Jan
26 Jan
4:02 p.m.
> So, anybody who claims to "duplicate"
an alignment disk with stock
> hardware, disunirregardless of what software is used, is an ignorant
> asshole.
On Sun, 26 Jan 2014, Chuck Guzis wrote:
Well, I don't claim to be able to duplicate a
digital alignment disk,
but I think one could be fabricated with a slightly modified "ordinary"
drive in good condition.
. . .
And I don't think that I'm an ignorant asshole.
Certainly not!
The key is "MODIFIED", even if the modifications do turn out to be trivial
to implement.
The claim of SOFTWARE having the ability to duplicate an alignment disk,
using UN-modified hardware is what I object to.
5:31 p.m.
New subject: Momemade Alignment disk
On Sun, 26 Jan 2014, Chuck Guzis wrote:
Well, I don't claim to be able to duplicate a
digital alignment disk,
but I think one could be fabricated with a slightly modified "ordinary"
drive in good condition.
I fully believe that YOU or TONY COULD create a usable digital alignment
diskette. I have NO doubts about that. The obvious problems don't seem
that much past what even I could kludge.
NOT necessarily a "duplicate".
If I understand it correctly, the Dysan Digital Diagnostic Diskette has
individual sectors "micro-stepped" out of position WITHIN a track! I have
no idea how they do THAT!
BUT, it would be relatively straight-forward to create a disk where entire
TRACKS are "micro-stepped" out of position - instead of "are you reading
more of the even-numbered V odd-numbered sectors?", it would be "are you
reading more of the even-numbered V odd-numbered TRACKS".
For data recovery, I had a couple of drives that I could move out of
alignment, although admittedly, I had no calibration, nor software control
of the movement, both of which would be essential for this task.
OR
with an off-axis hub, there would be an ANALOG V "digital"
"micro-stepped"
deviation in alignment within a track. With very careful positioning of
index, that could produce a result that could be used similarly to the
DDDD, maybe even usable with the same software! DDDD did not have
different alignment between the beginning V end of the same sector; this
would.
Even if it weren't possible to produce calibrated offsets, a small
collection of random offsets that then are measured COULD be used.
But, how would you go about measuring the position? Would that be done
with a special drive having a VERY narrow head, or would it have to be
done optically with a "developing" mix?
--
Grumpy Ol' Fred cisin at xenosoft.com
http://www.xenosoft.com/FPUIB
7:29 p.m.
New subject: Momemade Alignment disk
On 01/26/2014 02:31 PM, Fred Cisin wrote:
On Sun, 26 Jan 2014, Chuck Guzis wrote:
BUT, it would be relatively straight-forward to create
a disk where entire
TRACKS are "micro-stepped" out of position - instead of "are you reading
more of the even-numbered V odd-numbered sectors?", it would be "are you
reading more of the even-numbered V odd-numbered TRACKS".
For data recovery, I had a couple of drives that I could move out of
alignment, although admittedly, I had no calibration, nor software control
of the movement, both of which would be essential for this task.
In the bad old days, we made our own 100 tpi alignment diskettes. We
took a Micropolis drive, removed the stator from the stepper motor, so
that it was really nothing more than an empty shell with bearings and a
shaft. We then coupled a precision 100:1 reduction drive to the shaft
and another stepper and mounted the whole shebang onto a 3/4" slab of
aluminum. It took forever to step across the disk, but the result was
good enough for consistent calibration. A laser-interferometer setup
for reading position exactly would probably have been overkill.
Note that Micropolis drives were known for their leadscrew positioner
accuracy, thus the drive choice. They were slow--15 msec. track-to-track
probably because they used 4 steps per cylinder.
Microsoft continued along that line well into the 80s. The last design
I own is an 1115-series drive where the spindle motor, heads, and
positioner are all part of a solid assembly that pivots when the door is
opened. The stationary part is essentially just the hub "cone". To
compete with the taut-band school, it has a MOS Technology MCU to
provide buffered seek.
Note that leadscrew is also the positioner type used for almost all 3.5"
drives. I suspect the accuracy needs of 135 tpi floppies is a bit more
than can be reliably provided by a taut-band-and-capstan setup.
--Chuck
27 Jan
27 Jan
3:16 p.m.
New subject: Momemade Alignment disk
On Sun, 26 Jan 2014, Chuck Guzis wrote:
You have more confidence in my abilities than I do :-)
More seriously, I think everyone agrees that it is possible to make a
device that writes alignemt disks. It must be, becase said disks are
wirtten at the factory in thefirst place. I think it';s also likely that
such a deivc ecould be made by modifying a floppy drvie. What those
modifications consist of is not absolutely clear at the momen. But I
amlso agree with you that an unmodified drive cannot prodcue an alignment
disk.
-tony
Well, I don't claim to be able to duplicate a
digital alignment disk,
but I think one could be fabricated with a slightly modified "ordinary"
drive in good condition.
I fully believe that YOU or TONY COULD create a usable digital alignment
diskette. I have NO doubts about that. The obvious problems don't seem
that much past what even I could kludge.
5:54 p.m.
New subject: Momemade Alignment disk
> I fully believe that YOU or TONY COULD create a
usable digital alignment
> diskette. I have NO doubts about that. The obvious problems don't seem
> that much past what even I could kludge.
On Mon, 27 Jan 2014, Tony Duell wrote:
You have more confidence in my abilities than I do :-)
I think that you could modify the stepper mechanism on some drives to add
a calibrated offset - a simple verneir scale, or a micrometer head to
alter the radial position by known small amounts.
Then, although you would NOT have sectors offset relative to each other
within a track, you COULD write disk(s) with each track at a different
offset from its nominal position.
Software would then need to look at which TRACKS could be read, instead of
looking at which sectors within a track.
If it is more desirable to go with the offset hub, (and have sectors
differ in offset from each other within a track), . . .
either machine an entire replacement hub assembly, with the spindle mount
slightly off-center (surely the amount of offset required would not be
enough to run into serious difficulties with the off-axis load? and
rebalancing the off-center flywheel would not be that much different from
what we used to do to balance rotating automotive parts.)
Rather than machining an entire assembly, could you not bore out the
spindle hole in the hub and make a bushing?
And then, replace that bushing with a bushing with ID/OD not quite
coaxial?
(As you can see, my maching abilities vary between non-existent and
incompetent amateur)
More seriously, I think everyone agrees that it is
possible to make a
device that writes alignemt disks. It must be, becase said disks are
wirtten at the factory in thefirst place. I think it';s also likely that
such a deivc ecould be made by modifying a floppy drvie. What those
modifications consist of is not absolutely clear at the momen. But I
amlso agree with you that an unmodified drive cannot prodcue an alignment
disk.
It seems to me that an ANALOG alignment disk would require special heads,
and even the digital alignment diskette might be improved upon with some
slightly different heads. For example, using a 96tpi head for creating a
48tpi alignment diskette might make it easier to detect misalignment.
And custom heads, . . . ?
--
Grumpy Ol' Fred cisin at xenosoft.com
http://www.xenosoft.com/FPUIB
26 Jan
26 Jan
4:31 p.m.
Wow, I was just asking!
no need to bite my head off :)
I wonder about some of these "alignment" programs though.
You have to figure a few of them are just junk.
There was one that was only good for testing the speed of the drive,
you could adjust with a screwdriver. But that's all it did.
These things are becoming harder and harder to get ahold of.
The thread has been about the azimuth adjustment, getting head
replacements is now impossible.
1581 drives are next to impossible to find now.
How long before the current supply is gone?
Or how long before the caps on the boards go?
Eventually the c64 will be totally gone, left just to emulation.
DEC Vax systems are pretty close to the same state.
Amigas are starting to be hard to find.
I used to be able to take apart and replace chips in c64s,
you could read the code and understand it.
with only 38k of ram usable (aprox) it wasn't hard to understand the whole system.
nowadays, forget it.
Raspberry pi seems to have potential in this regard.
sorry for ranting, I just feel like great swaths of computing history is being lost.
And present technology has lost a certain special "magic" it used to have.
C64 was fun, a PC is a toaster, it's boring.
Dan.
Date: Sun, 26 Jan 2014 11:22:47 -0800
From: cisin at xenosoft.com
To: cctalk at classiccmp.org
Subject: RE: 1541 Alignment disk
I think I asked years ago about duplicating
these,
but is there a practical way to do that with just a 1541?
NO!
NO!
NO!
What you can get PRODUCED by a normal drive, is a NORMAL disk.
What you can get PRODUCED by a normal drive, is a NORMAL disk.
What you can get PRODUCED by a normal drive, is a NORMAL disk.
You CAN NOT produce an alignment disk using a normal drive with a normal
controller.
You CAN NOT produce an alignment disk using a normal drive with a normal
controller.
You CAN NOT produce an alignment disk using a normal drive with a normal
controller.
I mean, if you align a drive using a scope with
the disk,
then duplicate it, how reliable is that copy for alignment of other drives?
WORTHLESS.
What you create with the normal controller with normal drive is a NORMAL
disk. IT IS ABSOLUTELY NOT AN ALIGNMENT DISK!
A "digital alignment disk" is a disk produced using a special drive, that
DELIBERATELY has sectors written OUT OF ALIGNMENT, in order to see which
sectors (HOW FAR OUT OF ALIGNMENT, AND IN WHICH DIRECTION) can be read by
the drive. Doing so provides a "reasonable" level of measurement of how
far out of alignment the drive is, and which direction. A disk written
with a NORMAL drive is aligned for that drive, and can NOT check anything
except whether a given drive is close enbough to alignment with the drive
that created that disk to be able to reade it. People who think that
THAT is "correct alignment" really don't give a shit whether the drive is
accurately aligned, or where within the range that succeeds in reading
THAT disk it might be. It is "close enough" to be able to read/recover
disks written by that drive; it is NOT acceptable for writing disks,
particularly for distribution, or even exchanging with other people who
have been doing the same, and have drives ELSEWHERE in the range that
reads THEIR "known good" disk.
It is a BAD, STUPID IDEA!
If you take a yardstick, and use it to make marks on a stick, and then use
that stick to make marks on another stick, and continue to use each stick
to make the marks on the next stick, HOW MANY sticks can you make that you
would claim are accurate?
Disunirregardless of the alignment of the drive, ANY disks created by that
drive are aligned to that drive - they are ABSOLUTELY NOT a graduated
and calibrated series of misalignments - they are ALL aligned to that
drive. Yes, "piracy" programs (blow it out your ass if that offends you),
can make a "copy" of the disk. But THAT "copy" is aligned to that
drive,
it is NOT an alignment disk, and is absolutely totally useless for
checking alignment of anything.
An "analog" alignment disk can not be created with a "normal"
controller/drive combination. Instead of "normal" digital data/sectors,
it has SPECIAL tracks written by special hardware. They are analog tracks,
containing signals for testing drives, and a normal drive/controller can
read them, but can NOT write them.
So, anybody who claims to "duplicate" an alignment disk with stock
hardware, disunirregardless of what software is used, is an ignorant
asshole.
5:48 p.m.
On Sun, 26 Jan 2014, Dan Gahlinger wrote:
sorry for ranting, I just feel like great swaths of
computing history is
being lost.
And present technology has lost a certain special "magic" it used to have.
C64 was fun, a PC is a toaster, it's boring.
But THAT, we completely agree on!
The wondrous and fun technology of our youth seems to be gone forever.
--
Grumpy Ol' Fred cisin at xenosoft.com
http://www.xenosoft.com/FPUIB
27 Jan
27 Jan
2:57 p.m.
Wow, I was just asking!
no need to bite my head off :)
I wonder about some of these "alignment" programs though.
You have to figure a few of them are just junk.
There was one that was only good for testing the speed of the drive,
you could adjust with a screwdriver. But that's all it did.
A lot of drives (I forget if the 1541 is one fo them) have a stroboscopic
disk on the spindle. You adjust the motor speed so tht this appears
stationy under mains lighting (there are nomally 50Hz and 60Hz patterns
on the strobe). Some yeats ago I built a device with a few counter ICs as
a divider chain to flash some white LEDs at eitehr 100Hz or 120Hz
(rememebr a mains lamp flashes twice per cycle). I designed it so said
LEds were on 1/16th of the time. The result gave the clearest indication
of when a drive was on-speed that I have ever seen.
[Drives dying]
Or how long before the caps on the boards go?
This is not a major problem. Capacitors are still made.
Eventually the c64 will be totally gone, left just to emulation.
DEC Vax systems are pretty close to the same state.
I've said before that there are really on 2 families of VAXen I would
consider running. The first s the 11/780, the second the 11/730. In both
cases almost all the aprts are either stil lavaialble or can be
substituted (they are docuemtned well enough to know what to repalce them
by).
Amigas are starting to be hard to find.
I used to be able to take apart and replace chips in c64s,
you could read the code and understand it.
with only 38k of ram usable (aprox) it wasn't hard to understand the whole =
system.
nowadays, forget it.
One reason I stick to my classic computers...
Raspberry pi seems to have potential in this regard.
Does it? The Rpi is based around a custo-ish IC in a BGA pacakage. Said
IC is not avaialble sperately, and solderign BGAs is not something that
can be odne with hand tools.
The instruction set of the graphics processor is not documented
(offiically). So forget understnadig nthe system.
And it's not a small machine. There's 112Mbytes of RAM in there. Programs
are large. Forget tryign to understnad them all.
-tony
5:26 p.m.
> There was one that was only good for testing the
speed of the drive,
> you could adjust with a screwdriver. But that's all it did.
For SOME drives, that's what needs adjustment most.
I remember having frequently having to deal with alignment on Shugart
5.25" drives, but rarely having to do anything with the MPIs other than
setting motor speed.
On Mon, 27 Jan 2014, Tony Duell wrote:
A lot of drives (I forget if the 1541 is one fo them)
have a stroboscopic
disk on the spindle. You adjust the motor speed so tht this appears
stationy under mains lighting (there are nomally 50Hz and 60Hz patterns
on the strobe). Some yeats ago I built a device with a few counter ICs as
a divider chain to flash some white LEDs at eitehr 100Hz or 120Hz
(rememebr a mains lamp flashes twice per cycle). I designed it so said
LEds were on 1/16th of the time. The result gave the clearest indication
of when a drive was on-speed that I have ever seen.
Long ago, a friend took one of my old automotive timing lights and rigged
it up to trigger off of the mains voltage.
But, I've been pretty happy with software speed testing (on drives that
have an index signal), and managed just fine with that for speed
adjustment.
[Drives dying]
But, there are other parts, including head assemblies that are not so easy
to work around.
Or how long before the caps on the boards go?
This is not a major problem. Capacitors are still made. And it's not a small machine. There's
112Mbytes of RAM in there. Programs
are large. Forget tryign to understnad them all.
It's pretty small. I think that a LOT of them would fit on a bus. :-)
8:46 p.m.
On Jan 27, 2014, at 2:57 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
There?s a simple workaround for that: use the BeagleBone instead. Same basic concept, but
open hardware. Instead of an SOC from Broadcom whose details are secret, it uses one from
TI which is extensively documented in a free for the download PDF file ? 4500 or so pages
of it.
I?ve been using it (the BeagleBone Black). Nice, inexpensive, flexible. Already built an
add-on board for it, quite easy.
paul
...
Raspberry pi seems to have potential in this regard.
Does it? The Rpi is based around a custo-ish IC in a BGA pacakage. Said
IC is not avaialble sperately, and solderign BGAs is not something that
can be odne with hand tools.
The instruction set of the graphics processor is not documented
(offiically). So forget understnadig nthe system.
28 Jan
28 Jan
12:25 p.m.
Just in reference to your comment on the caps.common mythology is once the caps blow,
that's it, board is gone.
I'm not got at electronics, don't know how true that is.
But it reminded me of another old related question,could you today, build a brand new 1541
with current parts?
I dont mean emulated like the SD drives or whatnot,I mean a real, functioning, exact
1541.
Is it still possible to buy a brand new 6502, 6520, IC ?(I did a quick search, but my
google-fu sucks atm)
Dan.
From: ard at p850ug1.demon.co.uk
Subject: Re: 1541 Alignment disk
To: cctalk at classiccmp.org
Date: Mon, 27 Jan 2014 19:57:04 +0000
Wow, I was just asking!
no need to bite my head off :)
I wonder about some of these "alignment" programs though.
You have to figure a few of them are just junk.
There was one that was only good for testing the speed of the drive,
you could adjust with a screwdriver. But that's all it did.
A lot of drives (I forget if the 1541 is one fo them) have a stroboscopic
disk on the spindle. You adjust the motor speed so tht this appears
stationy under mains lighting (there are nomally 50Hz and 60Hz patterns
on the strobe). Some yeats ago I built a device with a few counter ICs as
a divider chain to flash some white LEDs at eitehr 100Hz or 120Hz
(rememebr a mains lamp flashes twice per cycle). I designed it so said
LEds were on 1/16th of the time. The result gave the clearest indication
of when a drive was on-speed that I have ever seen.
[Drives dying]
Or how long before the caps on the boards go?
This is not a major problem. Capacitors are still made.
Eventually the c64 will be totally gone, left just to emulation.
DEC Vax systems are pretty close to the same state.
I've said before that there are really on 2 families of VAXen I would
consider running. The first s the 11/780, the second the 11/730. In both
cases almost all the aprts are either stil lavaialble or can be
substituted (they are docuemtned well enough to know what to repalce them
by).
Amigas are starting to be hard to find.
I used to be able to take apart and replace chips in c64s,
you could read the code and understand it.
with only 38k of ram usable (aprox) it wasn't hard to understand the whole =
system.
nowadays, forget it.
One reason I stick to my classic computers...
Raspberry pi seems to have potential in this regard.
Does it? The Rpi is based around a custo-ish IC in a BGA pacakage. Said
IC is not avaialble sperately, and solderign BGAs is not something that
can be odne with hand tools.
The instruction set of the graphics processor is not documented
(offiically). So forget understnadig nthe system.
And it's not a small machine. There's 112Mbytes of RAM in there. Programs
are large. Forget tryign to understnad them all.
-tony
1:44 p.m.
On Jan 28, 2014, at 12:25 PM, Dan Gahlinger <dgahling at hotmail.com> wrote:
Just in reference to your comment on the caps.common
mythology is once the caps blow, that's it, board is gone.
I'm not got at electronics, don't know how true that is.
Not very. It?s possible for a capacitor failure to cause collateral damage, either from
the current surge or from the mechanical forces associated with the failure. But
generally you just replace the failed part and all is well.
I remember a board with a bunch of tantalum caps that blew right off the board because the
fab shop had installed them with polarity reversed. That startled the engineer working on
board debug, but he just replaced the misinstalled parts and the board was fine.
paul
1:59 p.m.
I meant more like they leak all over teh board...
Subject: Re: 1541 Alignment disk
From: paulkoning at comcast.net
Date: Tue, 28 Jan 2014 13:44:01 -0500
To: cctalk at classiccmp.org
On Jan 28, 2014, at 12:25 PM, Dan Gahlinger <dgahling at hotmail.com> wrote:
Just in reference to your comment on the
caps.common mythology is once the caps blow, that's it, board is gone.
I'm not got at electronics, don't know how true that is.
Not very. It?s possible for a capacitor failure to cause collateral damage, either from
the current surge or from the mechanical forces associated with the failure. But
generally you just replace the failed part and all is well.
I remember a board with a bunch of tantalum caps that blew right off the board because
the fab shop had installed them with polarity reversed. That startled the engineer
working on board debug, but he just replaced the misinstalled parts and the board was
fine.
paul
2:43 p.m.
On Jan 28, 2014, at 1:59 PM, Dan Gahlinger <dgahling at hotmail.com> wrote:
I meant more like they leak all over teh board?
Possibly. It?s an electrolyte, medium caustic. Wash with water, rinse with distilled
water, dry carefully. No problem.
paul
Subject: Re: 1541 Alignment disk
From: paulkoning at comcast.net
Date: Tue, 28 Jan 2014 13:44:01 -0500
To: cctalk at classiccmp.org
On Jan 28, 2014, at 12:25 PM, Dan Gahlinger <dgahling at hotmail.com> wrote:
Just in reference to your comment on the
caps.common mythology is once the caps blow, that's it, board is gone.
I'm not got at electronics, don't know how true that is.
Not very. It?s possible for a capacitor failure to cause collateral damage, either from
the current surge or from the mechanical forces associated with the failure. But
generally you just replace the failed part and all is well.
I remember a board with a bunch of tantalum caps that blew right off the board because
the fab shop had installed them with polarity reversed. That startled the engineer
working on board debug, but he just replaced the misinstalled parts and the board was
fine.
paul
6:16 p.m.
I meant more like they leak all over teh board...
Electrolytic capacitors can leak or explode but in my experience they don't
do it very often. Like anything else, they can be incorrectly specified or
a bad batch can cause problems. Batteries are far less commonly found in
electronic equipment than capacitors are but I've had more problems with
batteries that have leaked than capacitors. Yet nobody seems to spend
sleepless nights worrying about batteries in the way they worry about
capacitors.
Just in reference to your comment on the
caps.common mythology is once the caps blow, that's it, board is gone.
I'm not got at electronics, don't know how true that is.
7:47 p.m.
On Jan 28, 2014 5:17 PM, "Peter Coghlan" <cctech at beyondthepale.ie>
wrote:
Electrolytic capacitors can leak or explode but in my
experience they
don't
do it very often. Like anything else, they can be
incorrectly specified
or
a bad batch can cause problems.
Aside from the infamous incomplete-stolen-formula problem, I've only seen
them leak or explode when overstressed. Note that the closer to the maximum
rating you operate them, the shorter their life will be.
On the other hand, if you leave them unused for many years, the oxide layer
breaks down. It's a gradual process, and the effective maximum voltage they
can handle goes down. If you try to use them at the original rated voltage,
or anywhere above whatever max voltage they've deteriorated to, they will
be irreversibly damaged, which may or may not cause a seal rupture or other
visible (or audible) effects.
Applying a current-limited power supply to them can "reform" them, by
growing back the oxide layer in roughly the same way it was done when the
capacitor was originally manufactured.
On the PDP-1 restoration project, because we had a very strong bias against
replacing components unnecessarily, we used an incredibly overengineered
process to test the electrolytic capacitors and reform those that needed
it. For artifacts substantially more commonplace than the PDP-1, I'd
exercise care, but not to the extreme we went to on that project.
8:36 p.m.
Ok that leads to a question.
how often (x times per y years) should old equipment be powered on to safegaurd them?
drives, systems, etc?
How about turning on a hard drive and doing a read of the whole disk just to revive the
magnetic flux?
boot your vax once every x years just to get it going
same for c64s, etc
Date: Tue, 28 Jan 2014 17:47:11 -0700
Subject: RE: 1541 Alignment disk
From: spacewar at gmail.com
To: cctalk at classiccmp.org
On Jan 28, 2014 5:17 PM, "Peter Coghlan" <cctech at beyondthepale.ie>
wrote:
Electrolytic capacitors can leak or explode but
in my experience they
don't
do it very often. Like anything else, they can
be incorrectly specified
or
a bad batch can cause problems.
Aside from the infamous incomplete-stolen-formula problem, I've only seen
them leak or explode when overstressed. Note that the closer to the maximum
rating you operate them, the shorter their life will be.
On the other hand, if you leave them unused for many years, the oxide layer
breaks down. It's a gradual process, and the effective maximum voltage they
can handle goes down. If you try to use them at the original rated voltage,
or anywhere above whatever max voltage they've deteriorated to, they will
be irreversibly damaged, which may or may not cause a seal rupture or other
visible (or audible) effects.
Applying a current-limited power supply to them can "reform" them, by
growing back the oxide layer in roughly the same way it was done when the
capacitor was originally manufactured.
On the PDP-1 restoration project, because we had a very strong bias against
replacing components unnecessarily, we used an incredibly overengineered
process to test the electrolytic capacitors and reform those that needed
it. For artifacts substantially more commonplace than the PDP-1, I'd
exercise care, but not to the extreme we went to on that project.
29 Jan
29 Jan
11:21 a.m.
On Jan 28, 2014, at 8:36 PM, Dan Gahlinger <dgahling at hotmail.com> wrote:
Ok that leads to a question.
how often (x times per y years) should old equipment be powered on to safegaurd them?
drives, systems, etc?
How about turning on a hard drive and doing a read of the whole disk just to revive the
magnetic flux?
That?s not how disks (or tapes) work. You may be thinking of the read/restore cycle in
core memory (or the shift register cycling of bubble memory). For disks and tapes and
floppies, read is passive; it should not affect the stored flux but it most definitely
does not ?revive? it.
Reading media to get all the data and write it to new media may be worth doing, to deal
with the possibility of the media going bad. I suspect that?s more of an issue for tape,
which can become sticky, than for disks.
boot your vax once every x years just to get it going
I?m not sure that powering up systems ?just in case? is actually productive. Power up is
a stress for electronics. Minicomputers and beyond probably don?t mind much, but some
older mainframes were known to want to be powered continuously because you?d end up
repairing bits every power cycle. (CDC 6000 series comes to mind; I?m told that Illiac IV
had the same issue.)
paul
11:41 a.m.
boot your vax
once every x years just to get it going
I?m not sure that powering up systems ?just
in case? is actually productive.$
12:37 p.m.
> how often (x times per y years) should old
equipment be powered on to
> safegaurd them? drives, systems, etc?
> How about turning on a hard drive and doing a read of the whole disk
> just to revive the magnetic flux?
On Wed, 29 Jan 2014, Paul Koning wrote:
That?s not how disks (or tapes) work. You may be
thinking of the
read/restore cycle in core memory (or the shift register cycling of
bubble memory). For disks and tapes and floppies, read is passive; it
should not affect the stored flux but it most definitely does not
?revive? it.
Reading media to get all the data and write it to new media may be worth
doing, to deal with the possibility of the media going bad.
It also MIGHT help a little with lubricants that are starting to "harden"
1:09 p.m.
On 01/29/2014 12:37 PM, Fred Cisin wrote:
For media it self there are magnetic considerations (print through) and
other time related defects like oxide shedding. All media should be on
alternate media that has a known lifetime and is reproducible before
failure.
As to drives anything with lubricants have a clock ticking use or no.
Dust is also a problem so they shoudl be covered to avoid that.
If the environment is not benign then ruct/corrosion and possibly vermin
can attack.
Then you have the possibility of electrical problems that are age and
temperature (usually high temps are bad) related.
As to bubble memory I have two and I have no idea if they have
wearout or age issues. Any ideas on that? The ones I have are
the intel bubble memory modules (non pc ) each of 128K each.
Allison
> how often
(x times per y years) should old equipment be powered on to
> safegaurd them? drives, systems, etc?
> How about turning on a hard drive and doing a read of the whole disk
> just to revive the magnetic flux?
On Wed, 29 Jan 2014, Paul Koning wrote:
That?s not how disks (or tapes) work. You may be
thinking of the
read/restore cycle in core memory (or the shift register cycling of
bubble memory). For disks and tapes and floppies, read is passive; it
should not affect the stored flux but it most definitely does not
?revive? it.
Reading media to get all the data and write it to new media may be worth
doing, to deal with the possibility of the media going bad.
It also MIGHT help a
little with lubricants that are starting to "harden"
2:38 p.m.
Magnetic domains don't erode over time.
The bubbles in bubble memory should be there
for as many years as the circuits don't fail and the
package keeps chemicals out( K-years? )
The same for core memory. As long as the wires
are there it will hold until over written.
Rotating media has the problems of possible contact
( older hard drives and floppies ) and the media flaking
off.
All can be effected by strong external fields.
Bubble is especially designed to be effected by external
fields and can be corrupted easier that others, like
floppies.
From past experience
Dwight
3:08 p.m.
On Jan 29, 2014, at 2:38 PM, dwight <dkelvey at hotmail.com> wrote:
...Rotating media has the problems of possible
contact
( older hard drives and floppies ) and the media flaking
off.
Contact in older hard drives? Fixed head drives, yes. But older moving head drives all
unload the heads from the disk surface, and while spinning don?t have contact either.
paul
3:34 p.m.
You reminded me of another myth.
There were programs for the 1541 that were supposed to be used with disk cleaners.they
claimed to be able to lower the read/write head closer to the disk to achieve proper
cleaning.
a rather unknown but infamous fake copier (cruel copy) used these routines to try to
damage the headsby running it on a regular non-cleaner disk.
It also ran the "daisy" program (makes the drive sing the song daisy) which
isn't particularly good for your drive,and disabled the software stop check and
slammed the drive to track 100 (attempted) from track 1, full on at max speed into the
hardware stop (also not good for the drive),
it also attempted to format both the source and destination disks among other
"cruel" things, hence it's name.
There are a lot of "myths" of hardware out there, I think the 1541 generated
quite a few.Not sure how these got started.
Example I was always led to believe the magnetic flux on a disk (hard disk) needed
refreshing after a few years.I think this particular one came out of GRC. I've gotta
stop believing anything that guy says.
Dan.
Subject: Re: 1541 Alignment disk
From: paulkoning at comcast.net
Date: Wed, 29 Jan 2014 15:08:52 -0500
To: cctalk at classiccmp.org
On Jan 29, 2014, at 2:38 PM, dwight <dkelvey at hotmail.com> wrote:
...Rotating media has the problems of possible
contact
( older hard drives and floppies ) and the media flaking
off.
Contact in older hard drives? Fixed head drives, yes. But older moving head drives all
unload the heads from the disk surface, and while spinning don?t have contact either.
paul
4:13 p.m.
On 01/29/2014 12:08 PM, Paul Koning wrote:
Contact in older hard drives? Fixed head drives, yes.
But older
moving head drives all unload the heads from the disk surface, and
while spinning don?t have contact either.
Just deteriorating coatings, in most cases. I've got a batch of early
Conner drives that exhibit creeping flaws every time I power them up.
Nothing to be done about it.
--Chuck
3:23 p.m.
On 01/28/2014 05:36 PM, Dan Gahlinger wrote:
Ok that leads to a question.
how often (x times per y years) should old equipment be powered on to safegaurd them?
drives, systems, etc?
I'm not clear that periodically powering things on does anything
special. If it perchance does, once every 20 years should do. All I
need for that is for someone to devise a way to activate power from
within an urn of ashes.
I'll grant that reforming was a big issue in the case of older wet
electrolytics, but drying out of the electrolyte in my experience has
been more of a problem. I have a few older Boschert switchers from the
70s; many of the electrolytics are little more than empty cans by now.
Shrug. You replace what you can. Some of the Mallory "extended life"
caps (IIRC--I don't remember the exact term) are the worst offenders.
--Chuck
5:31 p.m.
From: cclist at sydex.com
---snip--->
Shrug. You replace what you can. Some of the Mallory
"extended life"
caps (IIRC--I don't remember the exact term) are the worst offenders.
--Chuck
I have a number of older Lambda supplies
with mixed electrolytics. Among them are
ones labeled "Long Life" and "Lambda".
Most every one of these has failed in my supplies.
I guess if it is an advertizing point, they will be
just the opposite.
Dwight
6:57 p.m.
On Jan 29, 2014 1:50 PM, "Chuck Guzis" <cclist at sydex.com> wrote:
I'm not clear that periodically powering things on
does anything special.
If it perchance does, once every 20 years should do.
I think I'd recommend no less than every 5 years for the electrolytics, and
preferrably more frequently than that. I'd probably power up for a few
hours each time, if the equipment hadn't seen any other use.
I'll grant that reforming was a big issue in the
case of older wet
electrolytics, but drying out of the electrolyte in my experience
has been
more of a problem.
The drying out depends on the brand and vintage. If the capacitor was
sealed properly when manufactured, and hasn't been abused (electrically or
mechanically), it shouldn't dry out for many years. We had few if any dried
out electrolytics in the then 40-year-old PDP-1, but many that needed
reformation after only a decade since last powered operation.
As far as I know, modern aluminum electrolytics still work the same way, so
they are still prone to oxide breakdown. It's a fundamental characteristic
of the product, not a manufacturing defect, unlike e.g. a substandard seal
or an incomplete stolen electrolyte formula. At least one aluminum
electrolytic capacitor manufacturer had an app note about reformation on
their web site when we did the restoration.
The oxide breakdown is a progressive degradation, not a step function, and
different circuits (even in the same product) operate the electrolytics at
diiferent actual working voltages (as compared to rated maximums), so it is
difficult to give a one-size-fits-all rule of thumb regarding minimum
operating intervals and periods.
7:33 p.m.
On 01/29/2014 03:57 PM, Eric Smith wrote:
The drying out depends on the brand and vintage. If
the capacitor was
sealed properly when manufactured, and hasn't been abused (electrically or
mechanically), it shouldn't dry out for many years. We had few if any dried
out electrolytics in the then 40-year-old PDP-1, but many that needed
reformation after only a decade since last powered operation.
Early switching supplies did not deal well with the old high-ESR
electrolytics. Many failed dry simply because the electrolyte cooked
out from internal heating.
As far as I know, modern aluminum electrolytics still
work the same way, so
they are still prone to oxide breakdown. It's a fundamental characteristic
of the product, not a manufacturing defect, unlike e.g. a substandard seal
or an incomplete stolen electrolyte formula. At least one aluminum
electrolytic capacitor manufacturer had an app note about reformation on
their web site when we did the restoration.
That's true--I've carefully reformed old electrolytics on old radio gear
successfully. However, the approach of using a variac on a piece of
gear to run it at low voltage with an eye toward capacitor reforming can
be a grave mistake when switching PSUs are involved.
I'd venture that if the equipment was made much after 1980, you're
probably safe in throwing full line voltage on it and waiting for the
smoke to clear. You'll probably end up replacing a few tantalums anyway.
Your mileage of course, may vary.
I have no idea if the new conductive polymer aluminum electrolytics will
require reforming--and by the time that's firmly established, I probably
won't be around to witness it.
--Chuck
2:09 p.m.
I don't understand where this mythology about
capacitors has come from. They
Nor do I, really...
The only thing I can think of is in valve (tube) amplifiers there's often
a coupling capacitor from the anode (plate) of the driver to the grid of
the output valve. If this goes leaky, it appliles a +ve bias to said
grid, the ouput valve conducts heavily, often damaging the valve and the
output trasnformer.
This is one capacitor that does fail quite often (a slight leak is often
enough to upset things) and which has someaht serious consequences (I
have sene the anode of an EL34 glow bright orange due to this).
So I guess there are times when it's important to be sure the capacitor
is good. But in 99% of computer evices, if a cpacitor fials it does no
otehr damage. And they don't fail that often.
get blamed for every possible kind of equipment
failure whether or not there
is evidence to suggest a capacitor might be responsible. It is routinely
suggested that any and every problem can be solved by something which has
come to be known as "re-capping" which I suspect means replacing all the
capacitors in a device. It has even been suggested that no vintage
restoration is complete without replacing all the capacitors.
YEs, I've heard that rubbish too...
I have had capacitors fail. In fact the last repair to a classic computer
device that I did was a dead shorted electrolytic capacitor. But I just
replaced that oen capacitor, not all the ones in the unit
And I reckon I've had more LSI ICs fial than capcitors, for all I have
used many more capaciutors.
As ever, I collect the symptoms, then think avout them before replacing
anything. If it's a capacitor that's failed, then of course I replace it.
But I don't just replacve capacitors in the hope it will cure the proble,m.
-tony
6:33 p.m.
I don't understand where this mythology about
capacitors has come from.
Because they are "mysterious" - not at all obvious what they do and how
they work to somebody who doesn't have a clue about electronics (but won't
admit to that). The concepts of resistors, or even diodes, are simpler
to grasp.
For entertainment, ask automobile mechanics what the "condenser" (a
capacitor) does, what the coil is and does, or even why the spark occurs
when the points separate rather than when they make contact.
They have NO IDEA how to test one, so therefore, "it MUST be changed when
you change the points" because they are somehow "matched" to each other,
and there certainly can't be any substitution from another model! (OK, one
with too short a connecting wire can be a hassle to install)
Most are not even aware that metal transfer from one side of the points to
the opposite is usually due to wrong capacitance.
"But, electronic ignition eliminates the whole problem, so there is no
need to know anything about that kind of stuff. And the USB OBDII reader
would tell you if you needed to know."
Admittedly, their symptoms can be peculiar - I once encountered a car that
seemed to pull to the right due to a bad condenser!! THAT was hard to
explain, until I went on a windy road while watching a scope. There was
an intermittent fault that came and went while turning, or even in the
small tilts in one direction but not the other in normal engine vibration.
11:39 p.m.
On Jan 28, 2014, at 5:16 PM, Peter Coghlan wrote:
I don't understand where this mythology about capacitors has come from. They
get blamed for every possible kind of equipment failure whether or not there
is evidence to suggest a capacitor might be responsible. It is routinely
suggested that any and every problem can be solved by something which has
come to be known as "re-capping" which I suspect means replacing all the
capacitors in a device. It has even been suggested that no vintage
restoration is complete without replacing all the capacitors.
Probably because replacing them does in a lot of cases fix what ails ya. I can't speak
for others, but I have fixed a lot of old electronics (monitors and computers both) and a
lot were fixed by "re-capping" or replacing one or several electrolytic
capacitors (and in a couple other cases tantalum or polyester). While they weren't
universally at fault, at least 75% of the cases I've worked on required replacing a
capacitor or three.
28 Jan
28 Jan
1:58 p.m.
On Tue, Jan 28, 2014 at 12:25:26PM -0500, Dan Gahlinger wrote:
[...]
But it reminded me of another old related
question,could you today, build a
brand new 1541 with current parts? I dont mean emulated like the SD drives or
whatnot,I mean a real, functioning, exact 1541. Is it still possible to buy a
brand new 6502, 6520, IC ?(I did a quick search, but my google-fu sucks atm)
Well, I doubt anybody is making 5.25" drive mechanisms any more, especially
nothing as cheap and nasty as those clunkers Commodore used, so that's your
first hurdle. For authenticity, you'd also need to machine yourself a fugly
case that's too big to fit anywhere convenient on the desk.
Which brings you to NOS parts, at which point you shouldn't have too much
difficulty sourcing the 6502 etc -- except they may well have been pulled out
of a 1541 in the first place!
2:32 p.m.
Probably a better solution would be to build the whole controller with modern hardware and
simply emulate the key pieces in an fpga. That would ensure a high degree of compatibility
and could even use the 1541's native rom image.
Sent from my iPhone
On Jan 28, 2014, at 12:58 PM, Peter Corlett <abuse at cabal.org.uk> wrote:
On Tue, Jan 28, 2014 at 12:25:26PM -0500, Dan
Gahlinger wrote:
[...]
But it reminded me of another old related
question,could you today, build a
brand new 1541 with current parts? I dont mean emulated like the SD drives or
whatnot,I mean a real, functioning, exact 1541. Is it still possible to buy a
brand new 6502, 6520, IC ?(I did a quick search, but my google-fu sucks atm)
Well, I doubt anybody is making 5.25" drive mechanisms any more, especially
nothing as cheap and nasty as those clunkers Commodore used, so that's your
first hurdle. For authenticity, you'd also need to machine yourself a fugly
case that's too big to fit anywhere convenient on the desk.
Which brings you to NOS parts, at which point you shouldn't have too much
difficulty sourcing the 6502 etc -- except they may well have been pulled out
of a 1541 in the first place!
3:36 p.m.
On Tue, 28 Jan 2014, Dan Gahlinger wrote:
Just in reference to your comment on the caps.common
mythology is once the =
caps blow=2C that's it=2C board is gone.
I'm not got at electronics=2C don't know how true that is.
Not especially. But, you may have to repair damage done when they blow
(electrical damage, to other parts, as well as filling in the big
charred crater with epoxy, and running wires to replace all of the traces
that once went through there.
But it reminded me of another old related
question=2Ccould you today=2C bui=
ld a brand new 1541 with current parts?
No, but you could build a slightly used one, or a brand new work-alike,
such as flash RAM that pretends to be a 1541
When you are done, you WILL be got at electronics!
4:04 p.m.
Just in reference to your comment on the caps.common mythology is once the =
caps blow, that's it, board is gone.
I'm not got at electronics, don't know how true that is.
In general when an electrolytic capacitor (the type that fails the
most) fails on such a board, it does notdo any ther damage. The unit
stops working, but will be fine if you replace the capcitor. And givne
that such capacitors are easy to obtain, it's not a big prblem to do
this. Well, unless you're one of the people who beleive that soldering is
impossible :-)
But it reminded me of another old related
question,could you today, build a=
brand new 1541 with current parts?
No, I don'tthink it is
It's been a logn time since I've been insdie a 1541, and tghere are at
least 2 main verisons of the main PCB. THe older one used anumber of
small chips and a ROM for the data encodign/decoding, the later one
(qhich ahs at least 2 sub-versions) used a 40 pin custom IC.
Needless to sya that custom IC is not goign to be available.
I don't think the 6502 is still beiugn made as a 40 pin DIL chip, is it?
There are plenty of them around, thouhg. Some of the TTL parts fro the
first verison fo the board may bbe no logner maide, but again, gettign
them as NOS is not hard.
So I think, if tyou wanted to, you could ake the controlelr board using
at orst NOS parts, and close equivalents, like EPROMs raehr htan ROMs I
also think, withoug trying it, you could fit the entier controlelr board
into an FPGA. Whehter you call that a 'clone' I don't know, It does the
smae things, it's the same design. But to me it's nto the same circuit.
The problkem, I think, is the mechcnail side. The 1541 is not a normal
drive + a controlelr board. It's a bare drive chassis + controller board.
What I mean by that is that all the elctroncis -- things like the head
amplifier, the stepper mtoor driver, etc are on the controller board. The
drive chasiss is just the motors, heads, etc.
So if ytou want ti to be 'origianl' you can't jsut use a standard drive.
You have ot use one with the sutiable motors, etc. And given that 5.25"
drives are n logner made, you are not foinf to find a current one.
My guess, again without trying it, is that given any 48tpi 5.25" drive
you could make a controller board using easily avialable parts (not
necessarily ones in currnet procduction, but you could probably do that
too if you don't maind it all going in one FPGA), that would act jsut
likea 1541. Whether that's a clone of a 1541 is open to debate, though.
-tony
4:36 p.m.
My favorite replacement so far is a SD card replacement for the 1541,and someone took the
time to make a "case" with stenciled sticker to make the SD card case look like
the original 1541 drive.
I can't find the url for it, but it looked like a real 1541, even with LEDs,but about
the size of a finger tip.
Oop, found it:
https://www.commodoreserver.com/Commodore/PhotoGallery/8DA44F45A0114349A0CF…
here:
https://www.commodoreserver.com/BlogEntryView.asp?EID=0B55CA414691476BBDCFE…
Dan.
From: ard at p850ug1.demon.co.uk
Subject: Re: 1541 Alignment disk
To: cctalk at classiccmp.org
Date: Tue, 28 Jan 2014 21:04:47 +0000
Just in reference to your comment on the caps.common mythology is once the =
caps blow, that's it, board is gone.
I'm not got at electronics, don't know how true that is.
In general when an electrolytic capacitor (the type that fails the
most) fails on such a board, it does notdo any ther damage. The unit
stops working, but will be fine if you replace the capcitor. And givne
that such capacitors are easy to obtain, it's not a big prblem to do
this. Well, unless you're one of the people who beleive that soldering is
impossible :-)
But it reminded me of another old related
question,could you today, build a=
brand new 1541 with current parts?
No, I don'tthink it is
It's been a logn time since I've been insdie a 1541, and tghere are at
least 2 main verisons of the main PCB. THe older one used anumber of
small chips and a ROM for the data encodign/decoding, the later one
(qhich ahs at least 2 sub-versions) used a 40 pin custom IC.
Needless to sya that custom IC is not goign to be available.
I don't think the 6502 is still beiugn made as a 40 pin DIL chip, is it?
There are plenty of them around, thouhg. Some of the TTL parts fro the
first verison fo the board may bbe no logner maide, but again, gettign
them as NOS is not hard.
So I think, if tyou wanted to, you could ake the controlelr board using
at orst NOS parts, and close equivalents, like EPROMs raehr htan ROMs I
also think, withoug trying it, you could fit the entier controlelr board
into an FPGA. Whehter you call that a 'clone' I don't know, It does the
smae things, it's the same design. But to me it's nto the same circuit.
The problkem, I think, is the mechcnail side. The 1541 is not a normal
drive + a controlelr board. It's a bare drive chassis + controller board.
What I mean by that is that all the elctroncis -- things like the head
amplifier, the stepper mtoor driver, etc are on the controller board. The
drive chasiss is just the motors, heads, etc.
So if ytou want ti to be 'origianl' you can't jsut use a standard drive.
You have ot use one with the sutiable motors, etc. And given that 5.25"
drives are n logner made, you are not foinf to find a current one.
My guess, again without trying it, is that given any 48tpi 5.25" drive
you could make a controller board using easily avialable parts (not
necessarily ones in currnet procduction, but you could probably do that
too if you don't maind it all going in one FPGA), that would act jsut
likea 1541. Whether that's a clone of a 1541 is open to debate, though.
-tony
4:56 p.m.
On Jan 28, 2014, at 4:04 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
It's been a logn time since I've been insdie a
1541, and tghere are at
least 2 main verisons of the main PCB. THe older one used anumber of
small chips and a ROM for the data encodign/decoding, the later one
(qhich ahs at least 2 sub-versions) used a 40 pin custom IC.
Needless to sya that custom IC is not goign to be available.
Perhaps not. I got a copy of "The Anatomy of the 1541 Disk Drive" at
my last vintage computing event with my local group. I should really
leaf through it some time. For those of you who can and will grok
PDF, though, it seems to be available online here:
http://www.jamtronix.com/files/c64_docs/anatomy_of_the_1541_disk_drive.pdf
It covers both the hardware and software (both ends) of the drive,
including a commented listing of DOS 2.6. Not a bad book.
I don't think the 6502 is still beiugn made as a
40 pin DIL chip, is it?
There are plenty of them around, thouhg. Some of the TTL parts fro the
first verison fo the board may bbe no logner maide, but again, gettign
them as NOS is not hard.
The NMOS versions are no longer made, but the Western Design Center
(the group that split off from MOS to make the original 65C02) still
makes a modern version of the 65C02 in 40-pin DIL that, as far as I
know, is a drop-in replacement (at least as much as any CMOS part can
be a drop-in replacement for TTL-interfaced NMOS parts). It still
retains the SO pin, which my fuzzy recollection says was actually used
by the 1541 firmware (and I've never seen it actually used anywhere
else, though it's a neat idea).
So I think, if tyou wanted to, you could ake the
controlelr board using
at orst NOS parts, and close equivalents, like EPROMs raehr htan ROMs I
also think, withoug trying it, you could fit the entier controlelr board
into an FPGA. Whehter you call that a 'clone' I don't know, It does the
smae things, it's the same design. But to me it's nto the same circuit.
You could easily fit the entire controller board into even a very
small FPGA and interface it to everything with appropriate level
conversion ICs. A lot of people might consider that "cheating",
though, and it certainly seems like it might violate the spirit of
the exercise, depending on what your goal is. Developing it with
separate 6502, 6522s, RAM and ROM ICs would certainly be a much
more interesting project, with a cooler board to show off at the
end of it.
But, as I and others have said, the mechanicals are the problem.
If you wanted to be in the business of manufacturing replacement
controllers for the 1541, you could do that, but it seems like a
rather small market. You could also do a halfway solution, that
made a disk controller for, say, PC-interfaced 5.25" and 3.5"
drives that would work on actual floppies, just not the original
ones. It's rather unlikely that you could make that work with
the original ROM image, but not entirely impossible. And it would
be kind of silly.
- Dave
4:45 p.m.
On Jan 28, 2014, at 12:25 PM, Dan Gahlinger <dgahling at hotmail.com> wrote:
But it reminded me of another old related
question,could you today, build a brand new 1541 with current parts?
I dont mean emulated like the SD drives or whatnot,I mean a real, functioning, exact
1541.
Is it still possible to buy a brand new 6502, 6520, IC ?(I did a quick search, but my
google-fu sucks atm)
Some yes, some no. There are plenty of NOS or pulled period-
appropriate 6502s available (Jameco, Unicorn, eBay), along with
their accompanying peripheral chips (6522s and 6551s are pretty
easy to find, 6526s not so much, but you don't need either of
the last two for a 1541). Or you can get new-production CMOS
chips from Western Design Center (65C02, 65C21, 65C22, 65C51)
that should be basically functionally equivalent.
I think the much harder task would be finding the drive
mechanisms, especially the heads. You could build a lot of the
parts yourself, especially with a 3D printer, but I have no
idea if anyone makes appropriate heads anymore (my guess is no,
and good luck getting them made for you for a reasonable price
unless you're making a million).
- Dave
29 Jan
29 Jan
12:24 p.m.
On Sun, 26 Jan 2014, Dan Gahlinger wrote:
Wow, I was just asking!
no need to bite my head off :)
True. Sorry about that.
But, I don't want them to hornswoggle you by selling you a program
that can't possibly do what they might claim.
A program might be able to copy a lot of things, some of them surprising,
but it certainly can NOT "copy everything", and a "copy" of an
alignment
disk made with an unmodified drive will not be usable for aligning disks.
--
Grumpy Ol' Fred cisin at xenosoft.com
26 Jan
26 Jan
1:12 p.m.
Isn't the alignment disc essentially a series of
concentric analog
sine-wave audio tracks, with each audio track recorded on the centerline of
a disc data track?
Actually, they are deliberately recorded eccentrically, so that as the
disk spins the ampllitude of the signal seen by the head changes. That's
what gives the catesye apttern.
It would seem that so long as the drive uses the same track spacing, one
disc could serve many mechanisms. Please correct me on that, if needed.
I beelive there are versiosn for drives with diffenent head azimuth
angles (the angle ebtwene the head gap and a radius of the disk). In my
experience this doesn;'t seem to matter to much. Yes, there is a head
azimuth test, but azimuth is rarely field-adjustable anyway and I've
never needed to check it. Radial alignment is the important one.
-tony
2:37 p.m.
On 01/26/2014 10:12 AM, Tony Duell meant to write:
I believe there are versions for drives with different
head azimuth
angles (the angle between the head gap and a radius of the disk). In my
experience this doesn't seem to matter to much. Yes, there is a head
azimuth test, but azimuth is rarely field-adjustable anyway and I've
never needed to check it. Radial alignment is the important one.
Azimuth was always a depressing thing to scope out on a brand-new,
not-yet-installed drive. Manufacturers didn't seem to set their QA
standards too high in that respect. Micropolis was particularly awful.
--Chuck
3:33 p.m.
Azimuth was always a depressing thing to scope out on
a brand-new,
not-yet-installed drive. Manufacturers didn't seem to set their QA
standards too high in that respect. Micropolis was particularly awful.
Azimuth was often not adjustable either. The drive service manual tells
you to check it, and if it's incorrect, to replace the head assembly.
Given that replacement heads re now totally unobtainable, the only reason
for needign to chec kit is to porve that's why the drive isn't working
proprely.
It's also not likely to change after manufacuter, unless the head
carriage is damaged in some way.
I think some of the drives wit hthe positioner aas a separate unit did
allowyou to move the positioner slightly and change the azimuth (and as a
by-product, also slightly change the track pitch). Perhaps I've been
lucky, but simply settign the posiitoner so that the head movement is as
near radial as I can get it has always worked for me.
Incidentally, if you want a shoick, try buying a new 3.5" no-name drive
(they do still exist) and put an alignment disk in it (the read amplifier
testpoitns are not hard to spot, even on drives with everything in one
ASIC). I've had new drives which are not correctly aligned.
-tony
3831
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