Path: utzoo!utgpu!news-server.csri.toronto.edu!qucdn!leek
Organization: Queen's University at Kingston
Date: Thursday, 25 Apr 1991 00:11:58 EDT
From: <LEEK@QUCDN.QueensU.CA>
Message-ID: <91115.001158LEEK@QUCDN.QueensU.CA>
Newsgroups: sci.electronics
Subject: Re: microprocessor wanted
References:  <119279@unix.cis.pitt.edu>

In article <119279@unix.cis.pitt.edu>, fmgst@unix.cis.pitt.edu (Filip
Gieszczykiewicz) says:
>
>        I need a microprocessor with the following specifications:
>
>        o       8-bit (16-bit would be nice)
>        o       ~10MHz clock
>        o       ability to address 64K of RAM (more would be nice)
>        o       BUILT-IN floating processor (that's the problem)
>        o       CHEAP (under $40)

I got a second solution to the problem if floating point is the main purpose
of the "chips".  68020 has a coprocessor interface and can be hooked up to 8
coprocessors. (All one need to do is to do address decoding for them.) Get 2
of them to control 16 of the 68881 math coprocessors.

16MHz  68020: $50 x 2   \  works out to be about $60 per "chip"
20Mhz  68881: $50 x 16  /

This solution can be cheaper if you opted for 16MHz 881 parts and ask for
a discount for 16 chips.

The amount of glue and board space is drammatically reduced - only 2 CPU's +
glue + 16 881 chip + 2 decoder chip.  SHould be able to fit on an AT style
expansion card with no problem...

>        P.S. I have yet to see a uP that does the above :-(

Then look at the problem differently.  Use a FPU instead of a CPU. :)

>_
>"The Force will be with you, always." It _is_ with me and has been for 11
>years
>Filip Gieszczykiewicz  "... a Jedi does it with a mind trick... " ;-)
>FMGST@PITTVMS  or  fmgst@unix.cis.pitt.edu "My ideas. ALL MINE!!"

K. C. Lee
Elec. Eng. Grad. Student