AMSYS29 floppies

Tony Duell ard at
Mon Nov 22 15:12:41 CST 2010

>  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 :-)

>  My Nicolet digital averager scope has several 2901s in it.
> They used these just about anywhere one needed a little
> more horse power.

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 

Three rivers diddn't use the 2901 in the PERQ, but they did use the 2910 
sequencer. I suspect they regretted that decision, it made sense in the 
origianl PERQ CPU with its 4K control store (the 2910 has 12 address 
outputs), but as the 2910 can't be easily extended ot a larger address 
width (unlike the 2909 or 2911 4-bit sequencer slices), all later PERqs 
with 16K control stores had a circuit commonly known as the '2 bit 
kjludge' (pun totally intentional!)

Apart from the obvious disk and tape controllers in some of my PDP11s,
other machines I've got that use the 2900 series are the Philips P854 (the
P800 CPU in 2900s, basically), a Xerox Daybreak, and the high-speed
language processor in my HP9845. I think there's a 2910 sequencer
(although no 2901s) on the 'transform sequencer bord' in my I2S model 75
image display, but I would have to check


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