PC disk drive termination

[Tony Duell]

Somebody earlier claimed that IBM didn't bother with termination on the 
disk drives in the PC family.

I've just looked in the 'Hardware Maintenance and Service' manual for the 
PC/AT. This is the only HMS manual I have (I don't normally bother with 
boardswapper guides), but I would be suprised if the same principles 
didn't apply to the PC.

Anyway, the manual says : 

'Diskette Drive

o The terminating resistor must be installed on drive A (top unit).

o In a system unit with 2 diskette drives, remove the terminating resistor
  from drive B (bottom unit) for proper operation.

o The diskette drive end of the signal cable is attached to diskette 
  drive A.

Fixed disk drive 

o The terminating resistor must be installed on fixed disk drive C (left 
  unit)

o In a system unit with 2 fixed disk drives, remove the terminating resistor
  from fixed disk drive D (right unit) for proper operation '

There are diagramss showing the location of the terminating resistor pack on
the drive PCB that I can't sensibly reproduce in ASCII.

-tony