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Need some help with 8 inch floppy drive...

Adventurer

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I'm about to aquire an IBM Displaywriter, with double floppy drive and no software. I do need to setup my old 286 PC to be able to read 8 inch floppies, so I guess I need some help.

First - if I understand correctly, I can use (or create) and adapter from 34 pin floppy cable to 50 pin cable for 8 inch drive. I ordered this adapter:
fdadap.jpg

So far so good. Next, I do need 50 pin cable. Can these SCSI cables be used?
s-l500.jpg

Next - which drive can you reccomend? I need to be able to write both - DS/DD and SS/SD floppies, at least judging from IBM displaywriter specifications. I'm thinking about getting a Shugart SA 851.
s-l1600.jpg

Last - as I understand, the drive motor is directly powered with AC power, and control board needs 24V and 5V DC?

Thanks in advance for any advice or help!
 

fritzeflink

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# 1st
The adapter is best. I have the older one. For SD format the floppy controller I prefer is

Adaptec AHA-1522A then
Adaptec AHA-1542B

Look at Registry of mainboards/floppy controller results
in http://classiccmp.org/dunfield/img/index.htm
In the CP/M FAQ are some answers, here is a link as I don't want to post it all.

Q14: Can I read my 8" disks with my PC?

http://oldcomputers.dyndns.org/public/pub/manuals/cpm-faq.txt

What drives you may use ?
I hope somebody other has an answer.

# 2nd

SCSI cable ?

I believe so .
 

modem7

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First - if I understand correctly, I can use (or create) and adapter from 34 pin floppy cable to 50 pin cable for 8 inch drive. I ordered this adapter:
I use the D Bit FDADAP adapter as well. Note that it needs to be powered via the 4-pin connector.

So far so good. Next, I do need 50 pin cable.
To cater for the data connector on my TM848-02 drive, I use the FDADAP-to-drive cable shown at [here].

Last - as I understand, the drive motor is directly powered with AC power, and control board needs 24V and 5V DC?
My TM848-02 drive only needs +24 Vdc and +5 Vdc. I power it via the setup shown at [here].

If you do not buy a tested drive, then do not be surprised if the drive is faulty. I had faulty capacitors in both of the drives that I purchased (separately).

Having technical documentation for the drive is good as well (e.g. for jumper configuration, for repair).

Don't accidentally buy a single-sided drive when you are after a double-sided one. That is what I did.
 

Adventurer

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If you do not buy a tested drive, then do not be surprised if the drive is faulty. I had faulty capacitors in both of the drives that I purchased (separately).

Having technical documentation for the drive is good as well (e.g. for jumper configuration, for repair).

Don't accidentally buy a single-sided drive when you are after a double-sided one. That is what I did.

Thanks, a very useful information it is! I have bought (ordered) Shugart SA-851, which I guess is a double sided drive after all. Still, getting it to work might be an interesting task, since usually no one lists them as "working", at least for the fair price not. I know how to replace the capacitors, and do have a soldering station, however, I hope there might not be some mechanical damage to drive heads or something, which can not be repaired unless having one more drive.

At least, so far:

FDADAP adapter - ordered, on the way
50 pin SCSI cable - ordered
8 inch drive - Shugart SA-851 - ordered
8 inch floppies - to be ordered
DC adapter for 8 inch drive - to be bought
286 PC with 5/14 floppy cables - in my possesion
All available software images for an IBM Displaywriter already downloaded, including ImageDisk software as well
Last, but not least - IBM Displaywriter, ordered, on the way, however, no documentation, no software provided.

Am I missing something in order to transfer the data?
 

Malvineous

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I would be interested to hear how this ends up working for you.

I have successfully used the KryoFlux (USB floppy interface) to read 8" disks with a Shugart SA-800 single-sided drive and it worked fine. I haven't tried connecting the drive to a real PC though.

You will likely need to adjust jumper settings on the Shugart drive to put it in PC-compatible mode (the factory default) if it has been changed to work with another type of computer. Some drives were made with soldered wire instead of jumpers so hopefully if you have one of these then it is already configured for PC operation.

If you're using it with a standard PC floppy controller, make sure you get the right 50Hz/60Hz version for your local mains power. Where I live the mains is 50Hz and most drives for sale are 60Hz, likely because someone imported the wrong drive and is trying to sell it again when they discovered it didn't work. If you get the wrong drive then the motor will run at the wrong speed (assuming the voltage is compatible) but I think the KryoFlux might be able to compensate for this. A real PC controller can't, though.

The FDADAP with SCSI cables works fine, as long as you can get the 50-pin edge connector at one end. The ones in your photo look fine. As well as +5VDC, +24VDC, and 240VAC @ 50Hz, my SA-800 also needs -5VDC to operate. The manuals can be found online and helpfully give part numbers for the various power connectors, along with current requirements for each voltage.
 

Adventurer

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Thanks everyone for advices and tips, and here are the news - I finally got all the components I needed, so I started to do some soldering/connecting job. The only problem - I had to use two power adapters for the drive, since local electronics shop did not have one with +24 and +5 V.

At the beginning things looked pretty well...P1001331.jpg

Later when the main connections and adapters were connected, it was time to connect FDDAP adapter and time to test the drive.

P1001332.jpg

Brand new old stock DS/DD floppies for testing:
P1001333.jpg

Test results:

Motor working - OK
Drive set up as 5.25 1.2 MB in BIOS - OK
Access light lits when switching on the PC, drive solenoid makes a click - OK
No errors on starting PC - OK
Drive access, format: fail
P1001334.jpg

I did notice, that the rails are not moving - I can manually adjust them, and they just stay where they are. It seems there is a problem either with electronics, or the rail motor itself. Maybe I can not use it with an MS-DOS format? Even then I would expect the rails to move at least...
 

Adventurer

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Forgot to write, that FDADAP adapter shows no progress when accessing drive - instead of track number there is "- -"
 

archeocomp

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I had one 8" drive which did not move head assembly. One 74 TTL on board was dead. I would double check step pulses are there and are wide/slow enough for your particular drive. When that's OK it is time to study the schematics. At least make sure there is TTL high level on pin 36 - the STEP signal of the drive when it is powered on and idle.

EDIT: FDADAP staying in unknown state indicates there might be problem with Track0, STEP and DIRECTION signals. Check Track0 levels when you move head assembly by hand.
 

MikeS

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...
Test results:

Motor working - OK
Drive set up as 5.25 1.2 MB in BIOS - OK
Access light lits when switching on the PC, drive solenoid makes a click - OK
No errors on starting PC - OK
Drive access, format: fail
...
The drive light should not light, nor should the HL solenoid engage until the drive is actually selected. Check the cable.
What drive number is the drive jumpered as?

m
 

modem7

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Drive set up as 5.25 1.2 MB in BIOS - OK
Note for later when you get the drive operational.

1.2M drives have 80 tracks. Like my TM848, the SA-851 has 77 tracks.

From memory:
* When I used an XT-FDC card, and DOS tried to format/access tracks beyond 77 (because DOS thought there were 80), I would hear a very nasty sound from the drive.
* When I used an FDADAP, and DOS tried to format/access tracks beyond 77, the FDADAP appeared to keep the drive at track 77.

So with the FDADAP, when I formatted a floppy via DOS, track 77 on the floppy ended up being formatted four times, first as track 77, then as 78, then as 79, then as 80.
The result was that the last six tracks ended up being marked as ..., 72, 73, 74, 75, 76, 80.
This meant that only 76 tracks on the floppy were usable, and I had to hope that DOS would not try to put anything beyond track 76.
 

Chuck(G)

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I'm sure you know this already, but I'll say it anyway. On 8" floppies, unlike 5.25" floppies, you need a write enable tab over the write-protect slot. 5.25" are exactly the opposite.

Also, 3M produced a line of floppies packaged with transparent red write-enable tabs. Apparently, they're too transparent for some drives. That one took a bit of work to discover... :)
 

sciencegirl100

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Building only the electronics you mean?

I can build (most likely) the mechanics of a drive and (definitely) the electronics.
All I would need are the components and schematics. I could even make my own board if needed.\
So, is there anyone with schematics of a DS/DD 8" floppy drive?
Also, what's a good reference on it's standards? (Such as speed, timings, data flow, etc.)
 

MikeS

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The result was that the last six tracks ended up being marked as ..., 72, 73, 74, 75, 76, 80.
This meant that only 76 tracks on the floppy were usable, and I had to hope that DOS would not try to put anything beyond track 76.
An interesting bit of info; thanks!
 

Chuck(G)

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I can build (most likely) the mechanics of a drive and (definitely) the electronics.
All I would need are the components and schematics. I could even make my own board if needed.\
So, is there anyone with schematics of a DS/DD 8" floppy drive?
Also, what's a good reference on it's standards? (Such as speed, timings, data flow, etc.)

A good place to start are the Shugart OEM documents on bitsavers. Shugart drives did tend to be the standard for 8" in the 70s.

Good luck on making those heads...
 

Shadow Lord

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So with the FDADAP, when I formatted a floppy via DOS, track 77 on the floppy ended up being formatted four times, first as track 77, then as 78, then as 79, then as 80.

The result was that the last six tracks ended up being marked as ..., 72, 73, 74, 75, 76, 80.
This meant that only 76 tracks on the floppy were usable, and I had to hope that DOS would not try to put anything beyond track 76.

Modem7,

Could this be bypassed using the DOS driver "driver.sys" to give formatting info to programs like format?

Also can't you can define format parameters on the command line for format.com:

https://technet.microsoft.com/en-us/...(v=ws.11).aspx

So IIRC this should work: format d: /a:1024 /t:77 /n:8 where d is your 8" drive. Since you specify /n: I don't BELIEVE you need the /8 switch. Please note this is for MS-DOS version of the format.com and not the windows version.
 

Adventurer

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Glad to see more info coming in - I believe there should be something like a "using 8 inch floppy drive for dummies guide".

Anyway, I spent a rather sleepless night, working with the drive. Replaced some bad caps, had a long, but finally eventful fiddling with jumpers - finally I did get a seek operation when turning on the PC. However, it was not seeking when trying to acces/format the drive
P1001335[2].jpg

Later, more jumpers, two more added, and finally heads started to work as expected. What a relief!.

Next, some of you are already laughing, and well, I was not even reading the forum posts, so I got "Drive protect error". Instead of looking in forum (or google), I thought it must be the jumper configuration (indeed - it is possible to disable write protect on this drive, by soldering two connectors). Only after this operation I found out, that all I had to do is put a piece of tape on the floppy side. Oh well.

DOS 5.0 format - started to work, but the drive was making weird noises, heads jumping over sectors, so I simply aborted the operation. My main goal was to restore a floppy image to test with an IBM Displaywriter. After some trials and errors with ImageDisk software, I was finally making some progress:

P1001342[2].jpg

However, IBM Displaywriter acted as if I had inserted a blank floppy disk. I decided to test making an image of the disk, and here the picture was not that happy - basically the program was unable to read anything that was written.

P1001344[1].jpg

I strongly suspected this might had to do something with writing SD image on a DD drive/DD floppy (the only speed I could write was 250k, however, the image was written with 500K speed - maybe this also could cause some compatibility problems). Then, when I thought that very soon I will have everything under control, came the unexpected - I was transfering CP/M image for a Displaywriter, which was DS/DD format, and in the middle of the process, the 40MB hard drive of my system crashed, together with MS_DOS 5.0, and images to be tested. The fact that I had no floppy drives connected to it (except an 8 inch drive) did not help me at all.

While I work with fixing my system, may I ask some questions I really need answers for:

* Is DS/DD drive compatible with SS/SD floppies in terms of writing/reading the disk? I'm starting to think that there might be a problem.
* Has anyone succesfully restored and run any of the floppy images for IBM Displaywriter on bitsavers?

Time to rest now, to be continued tomorrow...
 
Last edited:

Chuck(G)

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Or you could simply use ImageDisk for testing--there's a custom formatting dialog there.

The link produces a 404, BTW. But I believe that the article refers to the standard NEC PC98 formatting, which is, a double-sided format (i.e. won't work with a single-sided drive). This format is shared among all PC 98 media types; 8" 5.25" and 3.5" (eminently sensible). However, I'm not clear if later versions of non-PC 98 MS-DOS support the 8x1024 track format.
 
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