I've got one of these diagnostic diskettes, though I was never able to find
software suitable for using one with 8" drives.
If there's anyone out there who can tell me where I can beg/borrow/steal it,
I'd do that.
Dick
-----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 7:51 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.
>
>-tony
>
I've got hundreds of diskettes over 20 years old, and NONE have been losing
emulsion. I've had some of the jackets crack, and I've had some of the ones
which have gotten wet along the way stick in their jackets so they wouldn't
rotate, but the emulsion on those which would rotate, I've never had flaking
of the emulsion. Maybe that's because it's really dry here in Denver.
If you clean your disk heads from time to time, you'll probably not build up
enough glutch to damage a diskette.
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 6:38 PM
Subject: Re: Needed: 1 IBM 8" alignment disk.
>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.
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
Kevin,
I still have my C-64 and 300 baud modem. I know I have the Comms program
somewhere. I'll search for it and get back with you.
Ken
>===== Original Message From classiccmp(a)u.washington.edu =====
>Hello,
>
>I have a lovely C-64 with 1541 disk drive and original Commodore 300 baud
>modem.. but no software for the modem. Is anybody willing to make me a
>copy of some disk with the Comms program on it? Basic utilities would also
>be appreciated. I've considered making a cable to write with the drive on
>my linux box but it's just not worth the effort.
>
>Thanks,
>Kevin
"I wonder if it really is working most of the way (i.e. it can read ID
marks and even data) but there's a problem getting that read data to the
CPU (shift registers, bus drivers, etc)."
Are you trying this on your 8/I or 8/S ?
What you describe doesn't appear to me to be an alignment issue. Whether
the drive is in or out of radial alignment, the appearance of the data will
change as the relative position of head to track changes. I'd suspect index
alignment if the thing doesn't find the first sector on a track. On the
other hand, if it doesn't ever find a sector address mark, it's also
possible that the controller has a hardware flaw.
Have you tried this controller with a drive that works? Have you tried this
drive with a computer that works? Since I'm not familiar with the hardware
you're using, and since I'm not anywhere which would make sending you a
candidate drive possible if I even have one, I can't suggest much.
-----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 9:15 PM
Subject: Re: 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
>
>
>Do you mean it's physically damaging those disks? Or it's erasing them?
>Or what? Becase if it is, then the last thing you should do is feed it an
>alignment disk (for obvious reasons).
>
When I do a write the logic happily kills *needed* data on the disk. It does
not erase them,.... it kind of writes what it wants to them.
>Normally, of course, you get the system working well enough to
>format/write/read a bulk-erased disk. It can do that however badly
>aligned it is. And once it can do that it's safe to stick the alignment
>disk in. But I assume that like many DEC and DEC-compatible systems, it
>can't actually format a disk.
That's right... this drive is pre '74.(an Orbis drive inside - serial #4) .
No formatting possible.. all TTL.. but double buffered (really cool)...
about 170 ttl chips in the interface alone (8 boards)
This drive can be used on (according to the most recent manual):
PDP-11/20
PDP-8,8/s,8I
nova
hp 2100
varian 620 or 70 family
You just plug in one small interface board into the cage for each different
mini.
>
>In that case, what I normally do is to put in a factory-formatted scratch
>disk. Clip a 'scope to the outputs of the read amplifier and move the
>head positioner slightly to peak the read amplitude. Sometimes it's
>easier to find 2 points, one each side of the track, where the amplitude
>has fallen off by the same amount and then to set it midway between them.
>
I did that (mentioned above).. I had the scope on the head... It did not
need alignment but looks like it might need a few TTLs...
>Once you've done that, the drive should be working well enough to test it
>fully. I'd not trust the alignment for real data like that (although the
>last 2 drives I did this way were within spec when checked with a catseye
>disk). But at least you'll know if it's safe to use the alignment disk.
>
I was hoping to use an alignment disk as this drive is filled with TTLs and
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)
>Sorry, BTW, I don't have an 8" alignment disk. I wish I did...
>
>-tony
>
>
Hello all,
Although it's not *my* particular interest, a paper tape punch/reader
caught my eye while I was scrounging around some surplus stores over the
weekend and I thought of this group. I *know* you're going to ask the
manufacturer and model, and I have to say that I don't remember, but it
*wasn't* DEC, HP, IBM, or any other brand I recognized.
It looks like it was designed to mount vertically in a 19" rack, and it
is about 2 feet high, rack width, and about 6 or 8 inches deep. It has
what appears to be a serial interface, and it even has a fairly decent
size roll of unpunched tape loaded. It's in very good cosmetic condition
(except for the dust on it) and it appears to be complete. I don't know
if it works, but the little bin has a lot of punch debris in it, so it
did at one time, anyway!
If there's any interest in this item, I can go get more specifics on it.
I doubt they guy wants too much for it, but then again I haven't asked
him yet...
Regards,
Stan
-----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 8:36 PM
Subject: Re: Needed: 1 IBM 8" alignment disk.
>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.
Again, "eating" refers to the fact that when I try to write it is damaging
the format through the writing process thereby destorying more original IBM
software... It is a very clean drive and handles disks well.. (it just
doesn't find sectors most of the time)...
It isn't alignment as I can manually move the head very slightly back and
forth which does affect the data coming into the controller assembly but
does not help it find the actual sector... Therefore, hardware or an anlog
adjustment
I would like an alignment disk so I can use "their" tuning procedure to make
this drive work quickly. It has a number of adjustments including : Clock,
window, gap, etc...
I would know what to expect (data wise) as I am troubleshooting the boards.
PROBLEMS TO DATE:
Cold solder joints on the backplane... yuck! Resoldered the whole thing just
to get the drive to talk to the CPU... I expect 1 or 2 problems on the
boards which are keeping this drive from running nicely.
I try to restore things that are pre-8" but this drive was built for a
Straight-8,8/S so I *have* to get it going.
john
PDP-8 and other rare mini computers
http://www.pdp8.com
>
>Tim.
>
