Re: What is the absolute smallest instruction set do you need to make a working computer?

From	Jeff Barnett <jbb@notatt.com>
Newsgroups	alt.comp.os.windows-10, alt.windows7.general, comp.sys.ibm.pc.hardware.chips, comp.sys.intel, alt.comp.hardware.amd.x86-64
Subject	Re: What is the absolute smallest instruction set do you need to make a working computer?
Date	2019-09-22 10:52 -0600
Organization	A noiseless patient Spider
Message-ID	<qm8bto$efc$1@dont-email.me> (permalink)
References	(3 earlier) <ap-dnUOrRe8QYRvAnZ2dnUU7-QfNnZ2d@giganews.com> <qm6uuc$vvr$1@dont-email.me> <mZGdnWDii-WUnRrAnZ2dnUU7-UWdnZ2d@giganews.com> <qm750f$oga$1@dont-email.me> <3ImdnXOXwbOG7RrAnZ2dnUU7-e3NnZ2d@giganews.com>

Cross-posted to 5 groups.

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Yousuf Khan wrote on 9/22/2019 6:59 AM:
> On 9/22/2019 1:47 AM, Jeff Barnett wrote:
>> The machine I'm trying to recall is Turing Complete. In other words it 
>> can implement an interpreter that can "execute" any Turing machine 
>> with any input tape - it's a theoretical machine. If you are talking 
>> about a machine with real components, that's a horse of a different 
>> color and quite puny in comparison. This 2 register machine, with few 
>> instructions was all the theoretical rage some 60 or 70 years ago and 
>> was described in many text books. I thought your original question was 
>> fishing for what I described.
> 
> Well, I don't know anything about "Turing Complete" machines. If such 
> Turing machines can be run through any current general purpose computer 
> architecture, then this theoretical machine should be able to run it too.
> 
> The concept is not about artificial intelligence, but about general 
> purpose computing at its most basic level. About 2 or 3 decades ago, we 
> had the debate about RISC vs. CISC architectures. Without getting into 
> debates about which of those concepts won in the end, this is taking 
> that debate to the next level, and asking what is the most basic set of 
> instructions that can eliminate all other instructions? So they've 
> eliminated every other instruction, and replaced it with this one 
> instruction, called SUBLEQ, "Subtract Less Than or Equal To". It only 
> does subtractions on data, and branches only when the result is less 
> than or equal to zero. So this is the ultimate RISC architecture, the 
> OISC (One Instruction Set Computing) architecture.
> 
> The page below links to an OISC interpreter and tools.
> 
> Oleg Mazonka - Languages - SUBLEQ
> http://mazonka.com/subleq/

What I described has zip to do with artificial intelligence and could 
never be implemented in real circuits - the registers are of whatever 
size the computation needs. It's like a TM tape can get as long as 
necessary. Note that the theoretical machine had no memory other than 
its two registers and a "code" store. It also worked with minimum 
instructions but could do any computable task.
-- 
Jeff Barnett

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