23 Nov
2010
23 Nov
'10
9:01 p.m.
Hi Tony
I'll have to dig it out. It is in storeage right now
and I'll not get to it for at least 2 weekends.
Dwight
From: ard at p850ug1.demon.co.uk
Subject: Re: AMSYS29 floppies
To: cctalk at classiccmp.org
Date: Tue, 23 Nov 2010 18:40:05 +0000
On 11/22/10 4:12 PM, Tony Duell wrote:
Well, 2901s were fairly expensive chips in those days, and it's
certainly possible to do wider-than-four-bit math in a four-bit CPU. :)
Indeed it is (heck, there are bit-serial CPUs at the hardware level). But
I am still suprised. Is a 2901 doing floating-point maths really faster
than an 8-bit microprocessor (I am thinking of, say, a PCB with a
dedicated Z80 or similar on it).
Using a 2901 as a nubble-serial processor seems strange because the 16
internal registers are not going to be that useful (64 bits of storage,
OK, you could hold 2 32 bit numbers, I suppose). I would assume there had
to be some external register RAM, in which cae, why use thge 2901? Why
not just use an ALU chip. like the 74S181?
Does the manual for htis board contain schematics? Microcode sources?
Bow much control store is there, is it ROM or RAM, and what is the sequencer?
-tony I have a
S100 board that is said to be a math processor board
that has a single 2901 on it. I have the manual as well.
I find that strange. A single 4 bit slice is not that useful. I asusme
there arten;t 2903s as well :-)