Orthogonality and contrivedness

steve stutman steve at radiorobots.com
Sun Jan 4 12:59:19 CST 2009

One must have affection for any proc with instruction "GHI".

An 1802 prob also still somewhat in control of the Earthmade-machine 
most distant from Earth.


Tim Shoppa wrote:
> Chuck writes:
>> I work with both PICs and AVRs (my current project uses an 
>> ATMega128), but both instruction sets seem to me to be more than a 
>> bit contrived.  The AVR less so than the PIC, but still on the "odd" 
>> side of the ledger.
> Try programming an 1802 for a while. You'll know you're really into
> it when it seems "contrived" that all those other processors can
> only use a single of their registers as a program counter :-).
> Twisting my mind to switch to 1802 mode and back is a interesting
> experience.
> The smaller PIC's make perfect sense once you realize they're
> Harvard architecture. Bigger PIC's, I never really grokked.
>> I'm not a 430 evangelist (and suspect that it will never enjoy the 
>> popularity of the PIC or AVR, which is a shame). I'll work with any 
>> instruction set, but I know what I'd prefer to use.
>> It's curious that the MSP430's instruction set is close to the GI 
>> CP1600, where the PIC is descended from the very different 1650.
> To me it's perfectly obvious that the MSP430 is PDP-11 like, and
> in some ways even more orthogonal than the -11. The CP1600 was
> substantially less orthogonal, more Nova-like with some
> of the registers obviously intended for index use.
> Tim.

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