Re: Polysemy in programming langs (was: Why does the meaning of words change?)

John Cowan wrote:

>Ph. D. scripsit:
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>>Then there was the PDP-8, the first mini-computer IIRC,
>>introduced in the 1960s. The only way to store the value
>>of the accumulator into memory was via the instruction
>>DCA, Deposit and Clear Accumulator. This copied the
>>value to memory then set the accumulator to zero.
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>Yup.  The "accumulator" (AC), for younkers, was the main (and on some
>models the only) register, so-called because it was used to
>accumulate sums.  The PDP-8's instruction set was small enough
>that I still remember all of it:
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>AND: logically AND a memory location with the AC, leave result in the AC
>TAD: add a memory location to the AC, leave the result in the AC
>ISZ: increment a memory location; if it becomes zero, skip next instruction
>DCA: move AC to a memory location, clear AC
>JMS: move the program counter to a memory location, jump to the following
>     memory location (the PDP-8's subroutine-calling convention)
>JMP: jump to memory location
>IOT: I/O instruction: pass one of 8 commands to one of up to 64 devices
>     (the meaning of each command was device-dependent)
>OPR1: depending on various bits, clear or complement the AC or the "link"
>     (condition code), or rotate the AC one or two bits left or right
>OPR2: skip next instruction depending on the AC's value, sign, and/or the link
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How do you logically AND one memory location?  AND adjacent bits? (ie.
10111010 > (0)001100)

It does look like a rather difficult instruction set.  Like one of them
esoteric-type languages.  Now, if you coded that in punctuation marks
and made it three dimensional.it could work...

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