Date   : Mon, 11 Feb 1991 15:33:11 GMT
From   : zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!sdd.hp.com!cs.utexas.edu!hellgate.utah.edu!fcom.cc.utah.edu!cc.utah.edu!cc.usu.edu!slsw2@tut.cis.ohio-state.edu
Subject: Using 3.5" floppies instead of 8" floppies

In article <11375@uhccux.uhcc.Hawaii.Edu>, ralph@uhheph.phys.hawaii.edu
(Ralph Becker-Szendy) writes:
> Pin   Pin   Signal
> 50p   34p
> =================
> 12     4    Disk change (may be on other pins too, not very standarized)
> 22    34    Ready (some 5.25 and 3.5" drives have no ready)
>       16    Motor on (only some 5.25 and 3.5" drives)

Oh yeah. IBM put Diskette Changed on pin 34, so any 5.25" or 3.5" HD drive
that you buy these days does that. I've also never seen a 5.25" drive that
ignored Motor On, even way back in the old days.

I've also noticed that PC drive vendors tend to be soldering in the drive-
select jumpers these days. I was looking for a drive for a CP/M machine, and
had to look for a while before finding one that wasn't hardwired to be drive
1; that's because IBM put this funky twist in their drive cable that swaps
the drive selects around and gives then individual control over the drive
motors. Of course, the BIOS just goes ahead and turns on both drives at the
same time...
-- 
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Roger Ivie

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