Re: Emigration from Usenet [was: Re: PTD was the most-respected of the AUE regulars ...]

D <nospam@example.net> wrote:

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On Thu, 8 Aug 2024, Dan Purgert wrote:
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On 2024-08-07, Lawrence D'Oliveiro wrote:

On 07 Aug 2024 15:04:21 GMT, Aharon Robbins wrote:
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A CS professor I know told me this last week:
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      I'm one of the very few that teach Systems.  It amazes me
      that our PhD students almost all in AI have never heard of a
      program counter.

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“Program counter” ... is that a von Neumann thing?

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It's the thing that holds the address of the current instruction
being executed.
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Effectively, CPU's operate like this loop here
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 int pc=0;
 while (1) {
   execute_instruction (pc);
   pc++;
 }
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After that, 'execute_instruction' can be thought of as a big
conditional statement that actually performs the task -- moving data
between CPU registers, reading from RAM, whatever.

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Could it have been called instruction counter on some platforms?  My
memory is very hazy but I vaguely remember a register you could
manipulate directly from my assembler labs and the long gone days
when I thought computer viruses were interesting.

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Some architectures named it "program counter", others used the name
"instruction pointer", still others likely used "instruction counter".
If one searched through much of computer architecture history I'd say
one could find a least a half dozen names for it (used by different
architectures) if not more.
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