22 Nov
2010
22 Nov
'10
10:35 p.m.
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. :)
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 :-) Althoguh AFAIK DEC never used them in a PDP11 CPU.
There were, of
course, used i nteh floating point processors for some PDP11s, and in the
VAX11/730
And the KS10 as well. I wonder if there are any others; I don't
think so offhand.
One of my favorite uses of Am2901s is in the FPF11 floating-point
processor. For the non-PDP11-savvy, the FPF11 is a strange board that
can be used in both Qbus and Unibus systems by changing jumpers near the
card-edge connectors. It uses a 40-pin ribbon cable to plug into a
microm DIP socket in an F11-based PDP-11 (11/23 or 11/24).
-Dave
--
Dave McGuire
Port Charlotte, FL