[comp.sys.ibm.pc] 1.2M drive for compatible

wrd@tekigm2.UUCP (05/07/87)

Can anyone tell me how to get a 1.2Meg disk drive that will work with a Maxim
PC-XT compatible.  At present I have two 360k drives and want to add a third,
but 1.2M, drive to the system.  I also have a Seagate ST-225 hard disk drive.
I have been told that you can only install 1.2 M drives in true IBM's and yet
the Tandom AT clone that I recently purchased for an engineer under me has a
1.2M drive in it.  What gives?  Will they only work on IBM's?  Or only on AT's?
Or on AT clones?  Or what?  I physically have space for a 1/2 height disk
drive, have the power connection and a spare buss connection and a spare card
slot.  So what is it that I need?  IBM Bios ROM chips?

Thanks in advance,
--Bill Dippert--
tektronix!tekigm2!wrd

mjg@ecsvax.UUCP (Michael Gingell) (05/08/87)

In article <1720@tekigm2.TEK.COM>, wrd@tekigm2.TEK.COM (Bill Dippert) writes:
> 
> Can anyone tell me how to get a 1.2Meg disk drive that will work with a Maxim
> PC-XT compatible.

The 1.2 Meg drives need a special controller which can deliver data
at 500 kHz instead of the regular 250 kHz. Normally this is available
only on an AT, and as far as I know, the software to support it is in
the BIOS of the AT and not in DOS.

However you can add a 1.2Meg drive to a PC in one of two ways. Weltec
makes a specially modified drive  (I think the type # is M16P) which
rotates at 180 rpm which gives an effective data transfer rate of
250 kHz which makes it compatible with your regular PC controller.
They supply a device driver which handles the additional format.
You can get these drives from Priority One for around $169.

Also several companies are now offering disk controllers that run
on a PC or XT or PC/XT compatible and have the capability of
working with standard unmodified AT type 1.2 Meg drives. This is
a better solution as the data transfer rate is twice as fast. Look
in Computer Shopper for the sources for these.

Mike Gingell   ...decvax!mcnc!ecsvax!mjg
> 
> Thanks in advance,
> --Bill Dippert--
> tektronix!tekigm2!wrd