Arty computers

Chuck Guzis cclist at
Mon Feb 5 12:37:55 CST 2007

On 5 Feb 2007 at 8:39, M H Stein wrote:

> My, what a remarkable memory you have: pin 40, /PCIT (Program Counter Inhibit),
> also used to output a pulse on execution of an SIN (software interrupt) instruction,
> apparently used mainly by the control console.

Thanks, but my recollection of this was probably related to wondering 
what the pin might be used for, perhaps extending the instruction set 
since the upper 6 bits of each 16 bit instruction word was unused by 
the CP1600.  Had I just read it on a pinout chart without thinking 
about it, it would have have sunk below the surface of the swamp I 
call my memory.  In conjunction with that, I do recall that GI sold 
10-bit ROMs for instruction storage.


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