24 Nov
2014
24 Nov
'14
2:44 p.m.
On Mon, 24 Nov 2014, Chuck Guzis wrote:
One of the easier methods of crossing the old-new
divide is to replace
or add a 3.5" floppy drive to the XT and use 2D (not high-density) media
to exchange. Leave the other 5.25" floppy where it is. Of course,
you'll need the header-to-edge adapter and the power cable adapter, but
AFAIK, they're still available--as well as drive bracket adapters.
Once you
solved the power connector issue, you could usually find cables,
or . . .
use a fairly long AT cable, but use the middle floppy connector for the
FDC!, the FDC connector for the 3.5" drive, and the end floppy connector
for the other floppy drive.
Later versions of MS-DOS (I don't recall exactly
when, but I think it
was around 3.3 or earlier, have a DRIVER.SYS installable driver to
handle the full 720K)--otherwise, you may be restricted to writing 360K.
THAT would be version 3.20 of bothe MS-DOS and PC-DOS.
They also had DRIVPARM as a CONFIG.SYS "command", that would reconfigure
without adding another drive nor driver in [precious] RAM. But, that was
not documented in the PC-DOS manuals, and for reasons as yet unexplained,
would not work with the real IBM BIOS ROMs, although it did work [with
either PC-DOS OR MS-DOS] with Award, Phoenix, and several generic BIOS
ROMs.
Also, SOME non-generic OEM versions of 2.11 that were put out with laptops
supported 720K drives.
The actual type 3.5" drive doesn't matter
much--you can use an HD or DD
drive, so long as it's media-sense and not host-directed for density
(almost all are) and you use DD disks (or cover the media type aperture
on the floppy.)
Well, the "1.4M" media and the "720K" media was slightly different.
600? Oersted V 720? oersted, so it was close enough that you could usually
get away with using the wrong one.
--
Grumpy Ol' Fred cisin at xenosoft.com