Newsgroups: comp.sys.ibm.pc.hardware
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!csn!kessner!david
From: david@kessner.denver.co.us (David Kessner)
Subject: Re: Need info. about coprocessor in DTK machine
Message-ID: <1991Apr17.063713.1299@kessner.denver.co.us>
Keywords: DTK, coprocessor
Organization: Kessner, Inc.
References: <1991Apr16.173834.9949@lonex.radc.af.mil>
Date: Wed, 17 Apr 91 06:37:13 GMT


On the 386 machines with ONE co-processor socket (for either a 387
or Weitek)...  There is an "one ring" of pins that the 387 does not use,
but the Weitek does.  So when a 387 is installed, not all the pins are used.

Now here is the biggie...

There is only ONE way to put in a 387 (or compatable)-- putting it in
any other way will DESTROY the chip and will cause the machine to not
boot up!

The socket that the 387 goes into is square, with one corner chopped
off more than the others.  This is nice, since the 387 is also notched
in a corner.  Align the corners, and place the chip into the socket (with
the outer 'ring' of pins unused).  And that is it.

Now...  The DTK machine (I have a cached DTK 386/25) is misleading.  The
socket is hard to find the 'notch' on, and it is not in the same orientation
as the CPU.  You have to look for an OUTLINE that is printed around the
socket on the PC board in order to figure out where the notch really is.

In addition, you have to make sure that jumper W14 is shorted-- indicating
that there is a FPU present.  On my machine, the jumper is located on the
edge of the MB, near the power supply.  I have not figured out what this
jumper actually does, since it works in either position...

I fear that you put the 387/Cyrix in wrong, and burning it out.  This is 
a VERY common problem, tis sad to say.  Intel puts a very strong warning
in their 387 packages, but IIT (and obviously Cyrix) don't...

-- 
David Kessner - david@kessner.denver.co.us            | do {
1135 Fairfax, Denver CO  80220  (303) 377-1801 (p.m.) |    . . .
If you cant flame MS-DOS, who can you flame?          |    } while( jones);
