hardware multiply/divide functionality in CPUs

Eric Smith eric at brouhaha.com
Wed Mar 9 14:42:26 CST 2011


Chuck Guzis wrote:
 > And it was HUGELY expensive, by the time you got
 > the entire chipset (ca. $1000 IIRC).

People talk about "the entire chipset", but there wasn't such a thing.  
That would be similar to talking about a microcoded bitslice system 
using "the entire 2900 chipset"; the concept is meaningless.

A 432 system had varying numbers of chips of varying types.  The General 
Data Process was composed of two chips, so those were always used 
together, but aside from that constraint the number of chips of each 
type used in a system varied all over the place.

A minimal system would need one GDP (43201 and 43202), and one IP 
(43203).  The total cost for one piece each of the 5 MHz speed grade of 
those three chips in 1984 was $259.

 > I don't believe it ever saw
 > deployment in any commercial product

There were a few commercial customers, but I have no idea what they used 
it in.

 > National couldn't get the PACE off the ground--it was 16-bit, slow,
 > and took its own bus interface chips..

I don't think many of the PACE systems used National's special interface 
chips.  It's not clear that those chips even went into production.

 > By the time you were done, you had something that ran about
 > as fast as an 8085,

Not even.

Anyhow, that proves my point.  Hobbyists weren't interested in things 
that had a poor price/performance ratio, and Just because hobbyists 
didn't use things doesn't mean that they were only available to the 
military.




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