24 Jul
2006
24 Jul
'06
6:05 p.m.
On 7/24/2006 at 9:09 PM Brad Parker wrote:
I do, and I am sure they're on Bitsavers...
Be warned that the PERQ is not a simple CPU (the 16K control store
version, which uses PALs for some of the logic, and which manages to
implement more microinstructions as a result, contains over 260 ICs). And
it's somewhat tied to the PERQ memory circuitry too. And it's got a
graphics accelerator that you probably won't want.
Even so, look at the diagrams (and the tech manual). There may well be
some stuff there you can use..
If it's interesting, the MIT CADR has a 32 bit
alu using the 74181 and
uses the '182 for carry. The schematics are also on bitsavers. It's a
reasonably general microcoded 32 bit cpu. Not bad for it's day.
If it's a 20 bit CPU that the OP wants, perhaps someone has a set of prints
for the PERQ.
I've always been fascinated with the TI 74S481--a 4 bit slice in a 40 pin
I whould have a data sheet on that.
package, but with a lot of functionality inside. I
don't know if they're
unobtainium nowadays. The 1978 TI patent on it is here:
http://www.freepatentsonline.com/4224676.html. One curious aspect is the
"position" input pin: if the slice is the most significant, you put a
voltage higher than 3.6v on it; if the least significant, less than 0.8
volts; if in the middle, between 1.8 and 3 volts.
Odd!
As an aside, the Philips P851 uses a custom chip that's a 4-bit slice.
It's called SPALU (Scratch Pad (registers) and Arithmetic Logic Unit) in
the service manual. There's probably enough info in said manual to
recreate the chip if desparate (which I will be if I don't have 4 working
ones out of the 8 I have (4 in the P851, 4 on a spare board).
-tony