Ohio Scientific Challenger 4P/MF

From: Dave <dfnr2_at_yahoo.com>
Date: Mon Aug 2 07:13:12 2004

Hi Jeff,

The OSI systems typically used an MPI B-51 5.25"
floppy with a built-in data separator. You can use
any other 5.25" SS/SD floppy drive if you build your
own separator. The Aardvark Journal Vol. 2 #6 (scan
at http://osiweb/osiweb in the Aardvark Journal
section) contains a schematic for a data separator on
page 4. The discrete component values aren't readable
on that scan, but from another article, you need:

74LS121 chip
74LS38 open collector quad NAND
470pf cap between pin 10-11 of the '121
18kohm resistor and a 10k pot between pin 11 and +5V
If you use the 74LS38 instead of a 7400, then pull
pins 3,4 of the '121 high via a 1K resistor.

I have a two-part PEEK-65 (thanks to Earl!) article on
interfacing newer disk drives to OSI machines, which I
will try to scan and put on the site this week.


--- JMeyer101_at_aol.com wrote:

> Hello Graeme,
> Thank you! This should help alot. Apparently this
> computer uses a floppy
> drive. Do you happen to know where I can pick one
> up?
> Thanks again,
> Jeff Meyer

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Received on Mon Aug 02 2004 - 07:13:12 BST

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