Re: Is microprocessor an integrated circuit???
From: John Larkin (jjlarkin_at_highSNIPlandTHIStechPLEASEnology.com)
Date: 01/31/05
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Date: Mon, 31 Jan 2005 10:28:11 -0800
On Sat, 29 Jan 2005 22:03:08 GMT, Rich Grise <richgrise@example.net>
wrote:
>On Sat, 29 Jan 2005 10:44:54 -0800, John Larkin wrote:
>
>> On Sat, 29 Jan 2005 13:27:05 -0500, keith <krw@att.bizzzz> wrote:
>>
>>
>>>Sure, but if a processor can exist without a program counter a
>>>micro-programmed machine can exist without a micro-program counter. A
>>>counter is a means to an end. It's not an end.
>>
>> Some of the low-ends COPS machines used a pseudo-random shift register
>> instead of a program counter. That reduced prop delays and hardware
>> complexity, but sequential instructions hopped all over the place. I
>> know a guy who actually programmed one of these monsters (used it in a
>> commercial ignition timing strobe, with all sorts of tricky timing
>> loops) and he's still fairly coherent.
>>
>> There are a few web sites devoted to designing computer languages and
>> architectures with the worst possible structures, apparently unaware
>> that National beat them to it.
>>
>One notable thing (at least I've noticed) about a microprogram is that
>each instruction has the address of the next instruction somewhere in it.
>That's kinda what makes it a state machine; but if it's counting through a
>microprogram store, it's still executing a microprogram.
>
>Which still doesn't make it a microprocessor. I tried to make a funny
>about, "wouldn't the microprogram in a microprocessor be called picocode?"
>but apparently nobody got it, everybody's ignoring me, or it wasn't funny.
>
>Thanks,
>Rich
>
There were/are machines with three levels of coding: instructions,
microinstructions, and picoinstructions. 68K maybe?
John
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