I hadn't made the connection before

Jim Brain brain at jbrain.com
Fri Jun 2 11:48:37 CDT 2017

On 6/2/2017 11:26 AM, Chuck Guzis via cctalk wrote:
> On 06/02/2017 07:55 AM, Al Kossow via cctalk wrote:
>> A very odd version of the PDP-11
>> I did some programming on it for GI in the late 70's using their
>> GIMINI development system and cross-development tools on their Sigma
>> 9.
> I sold a bare CP1600 chip about a year ago to a collector.   "Odd" is an
> understatement. A 10-bit wide instruction word, with the upper 6 bits of
> the opcode unused.   Loading a 16-bit address took three words.
> Also, slow, very slow, with no I/O instructions.   A stripped-down
> instruction set (IIRC, exclusive OR and AND Boolean ops, but no
> inclusive OR).  We'd examined its possible usage, but determined that
> code would run slower on it than on most contemporary 8-bit CPUs.
> But, for 1975, notable because it's a 16-bit monolithic CPU among a
> handful of others (Fairchild 9440, MicroNova, National PACE, TI 9900)
This begs the question of why the CP1600 was designed that way.  I fail 
to believe that GI engineers were somehow less intelligent than the rest 
of the population, so what happened?  Upper Management dictate?  
Customer demand?  It would be interesting to know.


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