2.8M Floppy (Was: thinking of the "ultimate" retro x86 PCs -

Fred Cisin cisin at xenosoft.com
Thu Jun 2 22:09:43 CDT 2016

> > I hope that Chuck will correct some of the errors that I made below:

On Thu, 2 Jun 2016, Chuck Guzis wrote:
> I think you've pretty much got it.

>> Was it 4.00 that added 2.8M?
> Sounds right--but it may also be a matter of *which* 4.0.  MS or IBM?

Some GOOGLEing seems to show it as being 5.00

and, I left out 3.00 being first official support of 1.2M
I wonder whether the folks coding 1.2M support knew that it
wasn't for an 8" ?

> At some point, MSDOS decided that the hard disk would always be C:, with
> any additional removable drives trailing that.  That probably helped a
> lot.  And there was always a drive B:, whether or not a physical drive
> was present (if not, it mapped to drive A: with suitable prompting
> messages).

That seemed to be their intent starting with 5.00
However, when I put 5.00 on a 5160 with four floppies and motherboard 
switches properly set for that, the MS-DOS 5.00 INSTALL choked on wanting 
C:, but it worked fine when put on without using INSTALL.EXE (FORMAT/S on 
another machine with it installed, boot from that DOS5.00 boot floppy, 
SYS the hard drive, copy the files.)
That still worked when I replaced that 5160 motherboard with a 386 and 
generic AT four drive floppy controller!  The OS didn't seem to care about 
(But, I was surprised that the Cordata laser printer software refused to 
try to run on mewer than 8088 processor.  But, I had 4 different interface 
boards (such as Eiconscript) connected to an ABCD switch on that CX 

Thank you for the Ctrl-A tip on DRIVPARM.  Strangely, PC-DOS DRIVPARM 
worked for me with generic BIOS, but not real IBM BIOS on the same 
machine.   The FAIL with IBM BIOS was "Unrecognized command in 

I don't know which versions and/or which OEM'd versions had 8" support.
Probably ended with 6.00

Grumpy Ol' Fred     		cisin at xenosoft.com

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