[comp.sys.ibm.pc] IBM-XT Floppy upgrade

billm@ccicpg.UUCP (Morita Bill) (08/12/88)

	I am having trouble converting an old IBM-XT from a configuration
	of a single floppy (360k) and a single hard disk (20 Mb).  The 
	configuration I originally had worked fine until the full height
	IBM floppy drive died.  I replaced it with two Tandon half-height
	floppies (model 50-2).  The floppy controller is some unknown
	manufacture (I can't find any markings on the board).  The cable
	is the type with the "half-twist".  I have terminated things
	according to the instructions recieved with the drives.

	The problem is this: Only ONE drive will work, e.g. the first drive
	(the "a:" drive).  Both floppy drives function correctly when placed
	in the "a" drive position on the cable.  The cable checks out
	in that I can plug it in swapped end-for-end and the "a" drive
	functions correctly.  The only conclusion I can come to is that
	there must be some hardware change necessary.  Like a DIP switch
	on the floppy controller or the mother board.  None of the software
	can "see" the second drive.  Maybe I need a new BIOS ROM???

	Any help that anyone can give me would be much appreciated.
	Thanks (in advance)

			Bill Morita

cnee@wright.EDU (Cheng-Lee Nee) (08/14/88)

in article <19592@ccicpg.UUCP>, billm@ccicpg.UUCP (Morita Bill) says:
> References:
> 
> 
> 	The problem is this: Only ONE drive will work, e.g. the first drive
> 	(the "a:" drive).  Both floppy drives function correctly when placed
> 	in the "a" drive position on the cable.  The cable checks out
> 	in that I can plug it in swapped end-for-end and the "a" drive
> 	functions correctly.  The only conclusion I can come to is that
> 	there must be some hardware change necessary.  Like a DIP switch
> 	on the floppy controller or the mother board.  None of the software
> 	can "see" the second drive.  Maybe I need a new BIOS ROM???

There is a bank of DIP switch on the XT motherboard. The switch 7 & 8 are
for number of floppy drives installed. The settings are as follow:

	7=on  8=on   1 drive installed
	7=off 8=on   2 drives installed
	7=on  8=off  3 drives installed
	7=off 8=off  4 drives installed

Just change the switchs and DOS will recognize the drive B:

Cheng-Lee Nee