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);