Date   : Sat, 19 Mar 1988 17:17:25 GMT
From   : osu-cis!n8emr!oink!jep@TUT.CIS.OHIO-STATE.EDU (James E. Prior)
Subject: 8" floppy drive probles

In article <667@tetra.NOSC.MIL> budden@tetra.nosc.mil.UUCP (Ray A. Buddenberg)
writes:
>
>Agree with Jim that there is no real need to dump 8" drives.
>I've got a hybrid with both on my CPM workhorse.
>
>But there is one additional reason that 8" can be a liability
>in certain situations.  The drive motor is the only thing in
>the whole computer that does anything with 60 Hz.  Aboard ships, we
>had to trade our 8 inchers out because when the cooks fired up
>the stoves in the galley for breakfast, we got cycle sags.
>Which changed the drive speed.  The result was what we called
>'data smear', a phenomenon that made you a believer in backing 
>up your work.
>
>5" drives, which run on DC only don't have this problem (true for
>both hard discs and floppies).
>
>Rex Buddenberg

I sympathize.  Since the half height drives came out years ago, there
has been an easy solution.

All the 8" half height drives that I know about ran on DC only.  One
does need a hefty +24V supply for such beasts though.  Unfortunately,
these are still more expensive even at the flea markets than full
size 8" drives.  

Caveat: I bought a Tandon 848-2 brand new @ $450.  Tandon's 8" drives
were plauged with a long motor startup speed stabilization period.
Their drives would signal that they were up to speed before they should.
Some of the solutions to this problem were to delay the assertion of that
signal in hardware, or to add some kill time loop in software.  Another
solution was configure them to run all the time.  Unfortunately, this
drive always had the head loaded, so this was not a nice solution.  The
best solution was to get Shugart half height drives.  The had a direct
drive motor that would get up to speed very quick without fluctuating.
If any of y'all consider getting half height 8" drives, get Shugarts
if you can.  They had the feel of quality to them in many ways.  I
always heard good things about them, although I have no empirical
experience of my own with them.

For folks in 50Hz areas, there were typically two ways of doing AC 
motor stuff.  Some manufacturer had a dual pulley on the motor.  You'd
loosen the set screw, pull off the pulley, turn it over, put it back
on, and tighten the set screw.  The other (obvious) way was to have
a 50Hz motor.  The fifty Hz folks sometimes lived in areas where the
power line frequency varied, putting them in the same boat :-) as you
were in.
-- 
Jim Prior    {ihnp4|osu-cis}!n8emr!oink!jep    jep@oink.UUCP

Pointers are my friend.