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Teledisk w/Single Density Floppies

falter

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I am wondering what my best option is here. I have been trying to write an Osborne single density boot floppy with my 5170 without success. It does work for double side disks like the Morrow uses.

Is this just a matter of finding the right hardware? If my AT can't do it I'm not sure what else could.
 
Not all controllers can do single density. There are some that run on an AT that can but you have to try them. I don't know if there is a list someplace.
Dwight
 
What is my best bet? I tried a Kaypro 16, the AT, Commodore PC-10... none work. Am I looking to go older? Newer?
 
IIRC i think Sergey's 8-bit floppy disc controller can do FM ?
 
falter,
Dave Dunfield's Imagedisk Utilities include "TESTFDC.COM - Utility to evaluate floppy controller"

You can give that a try and determine what your FDC will write correctly.

Larry
 
A common way of adding FM support to a PC with 16-bit ISA is to add an Adaptec AHA-1542 series SCSI controller - preferably with the National Semiconductor FDC chip (small swirly "N" logo on the chip) rather than the Intel FDC (large "i" logo on the chip). You don't have to use the SCSI portion, but that does require disabling any existing FDC. However, I don't know if the FDC on IBM's 5170 FDC/HD card can be disabled without removing the entire card.

One can use the TESTFDC program included with ImageDisk to test if an FDC supports FM.

Another option is to use a Kryoflux or SuperCard pro attached to a newer computer. One can feed an ImageDisk or Teledisk file to the HxC software tool, export as a KF or SCP stream file, and write that stream file to a real disk.
 
A common way of adding FM support to a PC with 16-bit ISA is to add an Adaptec AHA-1542 series SCSI controller - preferably with the National Semiconductor FDC chip (small swirly "N" logo on the chip) rather than the Intel FDC (large "i" logo on the chip). You don't have to use the SCSI portion, but that does require disabling any existing FDC. However, I don't know if the FDC on IBM's 5170 FDC/HD card can be disabled without removing the entire card.

One can use the TESTFDC program included with ImageDisk to test if an FDC supports FM.

Another option is to use a Kryoflux or SuperCard pro attached to a newer computer. One can feed an ImageDisk or Teledisk file to the HxC software tool, export as a KF or SCP stream file, and write that stream file to a real disk.

Is it only about the controller or also the drive itself? I've tried on every vintage PC I have and it fails all of them on single sided.
 
Yes, it is entirely a limitation of the floppy disk controller. All 360k/1.2mb/720k/1.44mb drives can read and write FM single density *IF* the floppy disk controller supports it.
 
Ok. Well, I guess I'm gonna have to buy some O1 disks then. I'm surprised out of 10 computers of all different periods not one of them can do this.
 
There wouldn't be a way I could use my Morrow to format a bootable single density CPM disk for my Osborne would there?
 
Ok. Well, I guess I'm gonna have to buy some O1 disks then. I'm surprised out of 10 computers of all different periods not one of them can do this.

Here's the bizarre thing. On 8088-P1 systems, controllers that could do FM were unusual. Starting with some P3, P4 and later systems, the integrated floppy controller on the motherboard could very often handle it just fine; some can even do 128-byte MFM sectors.

So the rule of "what's old is better" is clearly not a fast and certain one.
 
Yeah I kind of tried everything. I have a PIII I use for this stuff and testfdc failed it. This Commodore 486 I have came closest... it formatted the disk but failed on write. I tried a PC10-II, PC-10-III, Kaypro 16, Compaq Portable III... nope. I wondered if the drive mattered because thE Commodore 486 machine has a 1.2mb floppy. I really can't think of any others in my inventory here that I haven't tried.
 
Okay here's an interesting one - I found an old converted P2 box.. it has an ASUS A7V400 board in it. TESTFDC passes the single density test no problem. It even formats and writes 128 MFM (but fails on verify). Anyway, since it passed the single density test I tried running image disk with it but... yeah... still won't write the disk properly. The disks come up as 250k.. I don't know if that matters.
 
It worked!

I was right - the drive does matter. I borrowed the 360k from my Commodore PC-10, and reran the test. It formatted 250k no problem. Then wrote the O1 disk with ease! Man am I glad I didn't toss that A7V400 box!
 
Yes, it is entirely a limitation of the floppy disk controller. All 360k/1.2mb/720k/1.44mb drives can read and write FM single density *IF* the floppy disk controller supports it.

You can't reliably use a 1.2mb drive to write a FM disk and read it on a 360K drive. The track width of the 1.2mb drive is too small. But, your right you can write it and read it as long as you don't mix them.
Dwight
 
Regrettably my Osborne cannot read what I wrote. I just can't tell if it's the drive or the disk. I've observed that the drive head sits at the back of the drive and just sort of clicks.
 
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