I'd be really interested in how you'd make your own alignment diskette.
Could you shed some light here? If this were in any sense straightforward,
I'd have made my own long ago. I suppose I could fiddle with one of my
PerSci drives, causing the head positioner to move as it would have to in
order to produce the famous "cat's-eye" pattern on track 38, but I believe
one would have to build special electronics to generate the sync reference
burst or pulse (depending on whether you prefer DYSAN or SHUGART alignment
diskettes) on tracks 1 and 76. Now, I've got no idea how to make the
azimuthal adjustments precisely enough that I'd trust the results.
Dick
-----Original Message-----
From: John B <dylanb(a)sympatico.ca>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Monday, November 29, 1999 6:46 PM
Subject: Re: Needed: 1 IBM 8" alignment disk.
>
>
>
>-----Original Message-----
>From: Richard Erlacher <edick(a)idcomm.com>
>To: Discussion re-collecting of classic computers
><classiccmp(a)u.washington.edu>
>Date: Monday, November 29, 1999 8:31 PM
>Subject: Re: Needed: 1 IBM 8" alignment disk.
>
>
>>Having aligned about 25 8" drives over the last 6 months, I can tell you
>>that if your drive is "eating" your diskettes, the problem isn't with
>>alignment. If it's damaging your diskette emulsion, it's likely that it's
>
>
>No.. My "eating" implies I am sticking in original IBM software disks to
old
>IBM minis and writing over the data on them. :-(
>
>>either missing the headload pad, or the head penetration is misadjusted.
I
>>don't know what the procedure for head penetration adjustment on your
>>particular drive is, but most drives seem to require a couple of feeler
>>guages and some glyptol to make sure it doesn't move when you're done.
>>
>>Before I'll consider LENDING anyone one of my no longer readily available
>>alignment diskettes, I want to be dead certain it won't be chewed up as
>>might happen with the misadjusted head penetration or missing headload
pad,
>>or written on as might happen with an inappropriately set-up drive or
>>controller. Even a $1k deposit won't ensure I get back a thoroughly
>useable
>>diskette, and I've not seen one for sale in over 15 years.
>
>The *moment* I get this drive up I'll be making IBM alignment disks for the
>planet!
>
>>
>>Dick
>>
>>-----Original Message-----
>>From: John B <dylanb(a)sympatico.ca>
>>To: Discussion re-collecting of classic computers
>><classiccmp(a)u.washington.edu>
>>Date: Monday, November 29, 1999 5:38 PM
>>Subject: Needed: 1 IBM 8" alignment disk.
>>
>>
>>>Before I find the highest building to jump off of, I though I might ask
>>here
>>>first....
>>>
>>>I have a Sykes 7150 8" floppy drive (negibus PDP-8I) that I have invested
>a
>>>half and hour in and have solved *most* of it's problems... It finally
>>talks
>>>to the PDP and I can select tracks, reset, read status, etc... once in a
>>>while read a sector.
>>>
>>>I need a single sided 128 byte record alignment floppy.
>>>
>>>When I do a read now, the drive stays busy forever looking for the sector
>I
>>>asked it for. (even if the head is on top of it). Since it was made in
>1974
>>>with TTL chips it is only bright enough to sit there and *wait* for the
>>>correct data to come by. An alignment disk would make life a lot easier.
>>>
>>>Anyone have one available? Please e-mail.
>>>
>>>P.S. The sooner the better.. this thing is eating original IBM software
>>>diskettes from the early '70s
>>>
>>>
>>>PDP-8 and other rare mini computers
>>>
>>>http://www.pdp8.com
>>>
>>>
>>>
>>
>>
>
Hi, all! I recently purchased a large batch of old QBus cards to expand
some of the systems in my collection, and one of the cards in the batch
is rather unknown to me... I know its some kind of disk controller,
guessing MSCP ST-506 but I'm wondering if its SCSI because i'm seeing
some resistor packs on the board that could be terminating resistors,
I suppose... anyways, here's the information:
(Label on top of large 48 pin IC)
"TD Systems Inc.
Lowell, MA - USA
VIK/QDT #2111"
(Label on 28 pin ROM)
"Viking
Q/B A4.0"
(Etching on card component side)
"211 00031 Rev. E"
(Another etching on component side)
"(C) 1987 Made in USA Assy 210-00031"
Physical characteristics - dual width board, 50 pin connector on board
with a single red LED near the connector.
I'd appreciate it if someone could clue me in on the identity of the
card - i'm rather curious as to what it is! :)
Thanks,
-Sean Caron (root(a)diablonet.net)
-----Original Message-----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Monday, November 29, 1999 9:48 PM
Subject: Re: Needed: 1 IBM 8" alignment disk.
>> I was hoping to use an alignment disk as this drive is filled with TTLs
and
>
>Hmmm... As I mentioned in another message, _most_ alignment disks won't
>really help you here. What you want is a 'diagnostic' disk -- one filled
>with valid (and known/simple) data patters -- tracks of sectors of all
>0's or all 1's, things like that.
>
>Fortunately, such a disk is fairly easy to make if you have any other
>machine with 8" drives. I normally use one of my CP/M boxes for this.
>
>Then you can conitunally read sectors from the disk. Using a 'scope you
>can see if the read PLL is locking -- is the read clock synchronised to
>the off-disk data. Once you've got that, you use a logic analyser
>(preferably) to look at the data stream and see if (for example) it
>detects address marks correctly (these are quite easy to recognise with a
>little practice.
>
>> pots... The manual has many test points with pictures using the alignment
>> disk. I have no idea if the IBM system diskettes I have actually have a
good
>> format on them (betting it)
>
>My guess is that _any_ disk will do for setting up the PLL. For other
>tests it helps if the data pattern is known and simple.
>
That's why I wanted one.. The manual actually calls it an alignment disk but
your right.. it's really just a diagnostic disk. I am identifying major
points on the schematics right now so I can quickly go through it with a
scope... (I *really* dislike 8" floppies)
>-tony
>
>
As a matter of fact, it's not unusual for floppy drives to lose their
alignment. What causes it is operating the stepping motor TOO SLOWLY. This
is frequently done in an effort to be conservative and allow the use of as
many different drives as possible, but the step rate is quite critical in
the long-term retention of alignment. Two alignment seem to go askew
frequently.
One, the most common, is index alignment. An alignment diskette has a pulse
or burst recorded nominally 200 microseconds after the start of the index
pulse, thereby allowing you or the technician to move the index sense LED
assembly once it's been loosened. I don't know why these get fouled up so
easily, but the vibration from running a 6 ms drive at 8ms might be at
fault. I'd say letting the springs POP the diskette out by snapping the
drive door open can do quite a bit to move the index sensor around.
Slamming the door shut won't help things either.
The radial alignment doesn't get fouled up as often as people think, but the
vibration I mentioned above is definitely the culprit, though rough handling
can cause problems as well. If you can hear your drive move its heads, as
you could with almost every PC FDD, then it's stepping too slowly.
Dick
-----Original Message-----
From: CLASSICCMP(a)trailing-edge.com <CLASSICCMP(a)trailing-edge.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Monday, November 29, 1999 6:29 PM
Subject: Re: Needed: 1 IBM 8" alignment disk.
>> Try formatting the disk. If you still can't read
>>back, an alignment disk won't help.
>
>I'd be willing to bet that the Sykes hardware in question isn't
>capable of formatting a raw 8" floppy. Remember, we're talking large
>boards packed full of SSI TTL here, and the formatting functionality
>usually wasn't present. (Besides, at the time all 8" floppies came
>preformatted.)
>
>> Check that the head(s)
>>are clean and, if single sided, that the pressure pad is not
>>tilted. It is rare that the alignment is off unless someone
>>fiddled with it.
>
>100% true. Unless it's been physically abused or someone decided they
>needed to "tweak" the alignment, it's probably right where it should be.
>
>And the advice to check the pressure pad is right on the money, too!
>
>Tim.
It is a Viking disk and tape SCSI controller. I scanned the manuals and did a
quick and dirty OCR of them. They are posted on Zane's site.
ftp://zane.brouhaha.com/pub/dan/viking_scsi/
Dan
-
(Label on top of large 48 pin IC)
"TD Systems Inc.
Lowell, MA - USA
VIK/QDT #2111"
(Label on 28 pin ROM)
"Viking
Q/B A4.0"
(Etching on card component side)
"211 00031 Rev. E"
(Another etching on component side)
"(C) 1987 Made in USA Assy 210-00031"
Physical characteristics - dual width board, 50 pin connector on board
with a single red LED near the connector.
I'd appreciate it if someone could clue me in on the identity of the
card - i'm rather curious as to what it is! :)
Thanks,
-Sean Caron (root(a)diablonet.net)
John B. wrote:
>P.S. The sooner the better.. this thing is eating original IBM software
>diskettes from the early '70s
Dick wrote:
>Having aligned about 25 8" drives over the last 6 months, I can tell you
>that if your drive is "eating" your diskettes, the problem isn't with
>alignment.
It depends on the rate of "eating", but for 25-year old floppies it's
not unusual to have a fair bit of flaking of the emulsion on the head
(lower) side. If there's any damage on the *top* side, that's definitely
the head load pad.
Tim.
>"I'd be willing to bet that the Sykes hardware in question isn't
>capable of formatting a raw 8" floppy."
>Is there any reason to beleive this device used standard SD soft-sectored
>discs, and wrote in the same format as IBM used?
Does the Sykes claim to be RX01-compatible? If so, it ought to be able to read
standard IBM 3740 floppies.
There are third-party-for-DEC-systems drives out there that don't
emulate RX01 or RX02, and use their own propietary data formats. The
AED 6200 is an example.
Tim.
Sorry for going a bit off-topic here. I normally have no qualm about
including my company email in my postings, it has resulted in some
interesting and useful dialogue since the topic *resembles* my work. But
a story that aired here in Houston yesterday gave me some pause to
think. It told of 3 workers at a midwest company who were terminated for
........ RECEIVING !! ... non-work-related email.
As usual with radio news, few details were provided. Was it spam? Was it
blatant personal mail? I wonder if anyone else has run across this
story. While I don't believe that my own company would be this
arbitrary, one has to wonder ..... if your employer Really wanted to get
rid of you .......
Nick Oliviero
"I'd be willing to bet that the Sykes hardware in question isn't
capable of formatting a raw 8" floppy."
Is there any reason to beleive this device used standard SD soft-sectored
discs, and wrote in the same format as IBM used?
