Early 3.5" Floppy Drives

[Scott Stevens]

On Mon, 12 Dec 2005 13:42:04 -0800 (PST)
Fred Cisin <cisin at xenosoft.com> wrote:

> > >January 1986, PC-DOS 3.20 supported 720K 3.5".
> > >Later in 1986, PC-DOS 3.30 supported 1.4M.
> On Mon, 12 Dec 2005, Chuck Guzis wrote:
> > The 720K 3.5" drive was introduced by IBM in 1986 as an option
> > for the standard PC-PC/AT product line.  What I recall about
> > the PS/2 was the support for DSHD and DSED 3.5 diskettes.  In
> > fact, drivers had been available earlier than PC-DOS 3.2 from
> > third parties for 720K 3.5" drives.
> 
> Numerous machines came out with 3.5" drives using "customized"
> versions of MS-DOS 2.11.
> 
> 2.11 and 3.31 seem to be the primary versions of MS-DOS that
> were customizable by OEMs.
> 
> 
> The "official", "standardized" support of 3.5" 720K in 3.20 was
> with use of DRIVER.SYS and/or DRIVPARM.  DRIVPARM was
> incompatible with IBM's BIOS, and therefore was undocumented in
> PC-DOS.
> 

I installed a drivparm line in the config.sys file of a true-blue
IBM PC-XT just this morning with good results.  However, it is a
machine with a BIOS extension on the controller card.  And it's
running MS-DOS.