mcguire at neurotica.com
Mon Nov 22 16:35:31 CST 2010
On 11/22/10 4:12 PM, Tony Duell wrote:
>> 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 :-)
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. :)
> 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
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).
Port Charlotte, FL
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