Date   : Wed, 10 Jan 1990 01:16:46 GMT
From   : samsung!usc!cs.utexas.edu!hellgate.utah.edu!cc.utah.edu!cc.usu.edu!slsw2@think.com (Roger Ivie)
Subject: 3-1/2" disc drives

In article <1388@atha.AthabascaU.CA>, tech@cs.AthabascaU.CA (Richard Loken)
writes:
> I recently embarked on a project to put 3-1/2" 1.44 Mbyte wafer drives in my
> dear old TRS80 Model II.  I randomly purchased 3 Panasonic drives and got out
> my dentist pliers and got the pinouts and some jumper info from Matsushita.
> 
> 
>   AT - PS2        (gag, yuck, my trash-80 may reject them)
>   A - B
> 
       AT - PS2 probably governs the operation of the Diskette Changed/Drive
       Ready line. ATs need diskette changed, and I had assumed that PS/2s
       did also.

       It is also possible that this controls drive selects in conjunction
       with the A - B option. ATs have a twisty in the cable so that all
       drives are jumpered as drive one. It is mildly possible that PS/2s
       do not, and the A - B switch would control the drive select (either
       0 or 1) if the thing is in PS/2 mode.

> How do you terminate these little rice boxes?  I see not a hint of a
termination
> avenue.

       These buggers usually have high-resistance terminators (abt 3k)
       in them that are hard wired on. Since the terminators are high
       resistance, it doesn't really hurt to have two terminated
       drives in the system.

==============================================================================
Roger Ivie

35 S 300 W
Logan, Ut.  84321
(801) 752-8633
==============================================================================