What's your guess? 100 instructions? 50 instructions? 10? Would you
believe just 1 instruction!? And that instruction is implied, you don't
even need an opcode for that! And you're not going to believe what that
one instruction is either! This video explains how it's possible.
https://youtu.be/jRZDnetjGuo
Interesting. In terms of commercially-successful CPUs the most minimal
I've worked with was the DEC PDP-8, which had 8 instructions (3-bit opcode).
On Sun, 22 Sep 2019 00:49:48 -0000 (UTC), Roger Blake wrote:
Interesting. In terms of commercially-successful CPUs the most minimal
I've worked with was the DEC PDP-8, which had 8 instructions (3-bit opcode).
A nand gate can implement all Boolean operations, can't it?
:)
On 9/21/2019 9:21 PM, Arlen Holder wrote:
On Sun, 22 Sep 2019 00:49:48 -0000 (UTC), Roger Blake wrote:
Interesting. In terms of commercially-successful CPUs the most minimal
I've worked with was the DEC PDP-8, which had 8 instructions (3-bit
opcode).
A nand gate can implement all Boolean operations, can't it?
:)
And so the answer is, the only instruction you need is a Subtract instruction! A special subtract instruction that branches only when the result is less than or equal to zero. The video explains how that works.
I haven't looked at the video but (trying to remember from the 1960s)
you need 2 registers and places to branch on either crossing 0.
Essentially one register is the right half and the other the left half
of the "tape" and you are working with 2 characters, etc., etc.. etc.
What's your guess? 100 instructions? 50 instructions? 10? Would you
believe just 1 instruction!? And that instruction is implied, you don't
even need an opcode for that! And you're not going to believe what that
one instruction is either! This video explains how it's possible.
https://youtu.be/jRZDnetjGuo
On 9/22/2019 12:04 AM, Jeff Barnett wrote:
I haven't looked at the video but (trying to remember from the 1960s)
you need 2 registers and places to branch on either crossing 0.
Essentially one register is the right half and the other the left half
of the "tape" and you are working with 2 characters, etc., etc.. etc.
This particular computer doesn't have any registers, it works directly
on memory. Now obviously in the background, the real chip might have
virtual registers that it uses as a buffer area, but that's completely
out of the control of the instruction set itself.
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.
https://en.wikipedia.org/wiki/One_instruction_set_computer
Concept proposed back in 1956.
It is a computational model used for teaching. It would be too slow for physical implementation. That it can be done doesn't mean anyone cares.
Yousuf Khan <bbbl67@spammenot.yahoo.com> wrote:
What's your guess? 100 instructions? 50 instructions? 10? Would you
believe just 1 instruction!? And that instruction is implied, you don't
even need an opcode for that! And you're not going to believe what that
one instruction is either! This video explains how it's possible.
https://youtu.be/jRZDnetjGuo
https://en.wikipedia.org/wiki/One_instruction_set_computer
Concept proposed back in 1956.
It is a computational model used for teaching. It would be too slow for >physical implementation. That it can be done doesn't mean anyone cares.
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/
On 2019-09-21, Yousuf Khan <bbbl67@spammenot.yahoo.com> wrote:
What's your guess? 100 instructions? 50 instructions? 10? Would you
believe just 1 instruction!? And that instruction is implied, you don't
even need an opcode for that! And you're not going to believe what that
one instruction is either! This video explains how it's possible.
https://youtu.be/jRZDnetjGuo
Interesting. In terms of commercially-successful CPUs the most minimal
I've worked with was the DEC PDP-8, which had 8 instructions (3-bit opcode). >However, one of those (OPR) permitted the programmer to combine several >operations into one instruction cycle by setting the appropriate bits.
The PDP-8 was a 12-bit word-oriented machine sold from 1965-1979. Early >models used discrete transistors, the last models were CMOS microprocessors. >There was also a serial model that operated on one bit at a time - slow!!
No stack was employed - subroutines worked via the caller writing the
return address into the first word of the called routine. Fun times!
Martin Gardner had an article about a "theoretical" 'primitive
computer using pulleys and ropes in place of transistors (or tubes).
In theory it would work, in practice there would be too much
imprecision from the slack/stretch in the ropes for it to work.
In message <5i4foelg0njuqoue46uudh75srbtfm83ak@4ax.com>, pyotr
filipivich <phamp@mindspring.com> writes:
[]
Martin Gardner had an article about a "theoretical" 'primitive >>computer using pulleys and ropes in place of transistors (or tubes).Babbage (arguably only with modern materials) made a mechanical machine >work. There are the mechanical equivalents of squaring circuits,
In theory it would work, in practice there would be too much
imprecision from the slack/stretch in the ropes for it to work.
thresholds etcetera. Electronic computers could be made to work with
three or four voltage levels rather than two - it just reduces the noise >margin, which puts limits on speed and distances. Presumably a
pulleys/ropes machine could be made, as long as there were thresholds,
and the mechanical equivalents of amplifiers (a rope-operated clutch >perhaps? I'm not really a mechanical engineer).
"J. P. Gilliver (John)" <G6JPG@255soft.uk> on Sun, 22 Sep 2019
21:15:45 +0100 typed in alt.windows7.general the following:
In message <5i4foelg0njuqoue46uudh75srbtfm83ak@4ax.com>, pyotr
filipivich <phamp@mindspring.com> writes:
[]
Martin Gardner had an article about a "theoretical" 'primitiveBabbage (arguably only with modern materials) made a mechanical machine
computer using pulleys and ropes in place of transistors (or tubes).
In theory it would work, in practice there would be too much
imprecision from the slack/stretch in the ropes for it to work.
work. There are the mechanical equivalents of squaring circuits,
thresholds etcetera. Electronic computers could be made to work with
three or four voltage levels rather than two - it just reduces the noise
margin, which puts limits on speed and distances. Presumably a
pulleys/ropes machine could be made, as long as there were thresholds,
and the mechanical equivalents of amplifiers (a rope-operated clutch
perhaps? I'm not really a mechanical engineer).
It is funny in a way. Garden was reporting a supposed "discovery"
of a "computer" discovered on a south pacific island. Yes, one could probably be made to work. Wintergatan - Marble Machine has made what
was originally a CGI video into a working machine. <https://www.youtube.com/watch?v=IvUU8joBb1Q> A fascinating study in
its own right.
On 2019-09-22 8:36 p.m., pyotr filipivich wrote:
"J. P. Gilliver (John)" <G6JPG@255soft.uk> on Sun, 22 Sep 2019
21:15:45 +0100 typed in alt.windows7.general the following:
In message <5i4foelg0njuqoue46uudh75srbtfm83ak@4ax.com>, pyotr
filipivich <phamp@mindspring.com> writes:
[]
Martin Gardner had an article about a "theoretical" 'primitiveBabbage (arguably only with modern materials) made a mechanical machine
computer using pulleys and ropes in place of transistors (or tubes).
In theory it would work, in practice there would be too much
imprecision from the slack/stretch in the ropes for it to work.
work. There are the mechanical equivalents of squaring circuits,
thresholds etcetera. Electronic computers could be made to work with
three or four voltage levels rather than two - it just reduces the noise >>> margin, which puts limits on speed and distances. Presumably a
pulleys/ropes machine could be made, as long as there were thresholds,
and the mechanical equivalents of amplifiers (a rope-operated clutch
perhaps? I'm not really a mechanical engineer).
It is funny in a way. Garden was reporting a supposed "discovery"
of a "computer" discovered on a south pacific island. Yes, one could
probably be made to work. Wintergatan - Marble Machine has made what
was originally a CGI video into a working machine.
<https://www.youtube.com/watch?v=IvUU8joBb1Q> A fascinating study in
its own right.
Absolutely wonderful machine and a brilliant inventor/builder. I didn't
know it existed.
| Sysop: | Keyop |
|---|---|
| Location: | Huddersfield, West Yorkshire, UK |
| Users: | 292 |
| Nodes: | 16 (2 / 14) |
| Uptime: | 191:16:11 |
| Calls: | 6,616 |
| Files: | 12,166 |
| Messages: | 5,315,205 |