Re: GS Crashing: copying files and Apple hi-speed SCSI (?)

[crash!vmbb!pro-newton!pro-dan!danb (Dan Brown)]

In <32j5tl$n8v@eis.calstate.edu>
gachenb@eis.calstate.edu (Greg R. Achenbach) writes:

>1)  It seems that proper SCSI function depends on 3 things - termination, 
>termination power, and magic.

        Termination, term power, and good cables take care of 95% of the
problems.  Voodoo is for the other 5%.

>2)  The RamFast provides both termination and termination power.  The 
>Apple HS SCSI provides termination, but not termination power.  The 
>original Apple SCSI provides neither.

        Mostly correct.  Some newer models of the HS SCSI do provide term
power to their own terminators.  Unfortunately, there's no way to tell them
apart.

>3)  Drives vary in whether they provide termination, termination power, 
>and how much magic is necessary to get them to run.

        Mostly true.  Most drives have a place to mount terminators on the
drive itself.  To tell if terminators are present, on most drives, look for
three ~7/8" long resistor packs, end to end, right near the 50-pin header at
the back of the drive.

        If I can figure out how to do it, I'll try to upload a GIF to c.b.a2
tomorrow explaining how to modify the Apple II SCSI Cards to supply term
power.  I'll also look for info on how to mod the drives.  You run a diode
from the +5v source to pin 25 or 26 on the header, but I don't remember what
kind of diode.

 --
Dan Brown
pro-dan!danb@pro-newton.cts.com