ratazzie@lonex.radc.af.mil (E. Paul Ratazzi) (04/17/91)
I have a DTK 25MHz 386 machine. The model number seems to be KEEN-2503 or something like that. I am trying to install a Cyrix 83D87 coprocessor. When I place the coprocessor in the 121-pin Weitek socket (the Cryix is supposed to be able to go in a Weitek socket or a 68-pin 80387 socket) the machine will not boot up. The BIOS setup says that the coprocessor option is set to autodetect. My questions: 1. Does anybody who has a similar DTK machine know if there are jumpers or other settings that need to be changed when installing a coprocessor? 2. Some computers have 2 sockets: one for a Weitek and one for a 387. I saw only a Weitek socket. Is there a 387 socket hidden somewhere (under the hard disk maybe)? 3. Anybody know a tech support line for DTK? TIA, -- E. Paul Ratazzi | ratazzie@lonex.radc.af.mil Microelectronics Reliability Division | COMPMAIL: e.ratazzi Rome Laboratory (USAF/AFSC) | (315) 330-2946 "Exploring the Invisible Frontier" | DSN 587-2946
david@kessner.denver.co.us (David Kessner) (04/17/91)
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);