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What is the absolute smallest instruction set do you need to make aworking computer?
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 Yousuf Khan |
#2
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What is the absolute smallest instruction set do you need tomake a working computer?
On 2019-09-21, Yousuf Khan 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! -- ----------------------------------------------------------------------------- Roger Blake (Posts from Google Groups killfiled due to excess spam.) NSA sedition and treason -- http://www.DeathToNSAthugs.com Don't talk to cops! -- http://www.DontTalkToCops.com Badges don't grant extra rights -- http://www.CopBlock.org ----------------------------------------------------------------------------- |
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What is the absolute smallest instruction set do you need to make a working computer?
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? |
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What is the absolute smallest instruction set do you need to makea working computer?
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. Yousuf Khan |
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What is the absolute smallest instruction set do you need to makea working computer?
Yousuf Khan wrote on 9/21/2019 10:46 PM:
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. -- Jeff Barnett |
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What is the absolute smallest instruction set do you need to makea working computer?
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. |
#7
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What is the absolute smallest instruction set do you need to make a working computer?
In message , Roger Blake
writes: On 2019-09-21, Yousuf Khan 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 first computer I learnt on had 8 instructions (3 bit opcode); it was a "computer" by Mr. Parr's definition of having a conditional jump among its op.s [as opposed to a programmable calculator - common at the time, 1970s, which didn't], where the decision was based on the result of (in this case) previous instructions. (The one-opcode answer given above qualifies, as it is subtract-and-jump-if.) 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! BRENDA (BaRnardian Electronic Numerical Demonstration Apparatus) was a 7-bit machine (16 memory locations); it _was_ a serial machine, also operating in ones complement, instead of the now-universal twos complement. It looked like everybody's idea of a computer then: a wall of filament bulbs (one for each bit in each memory location, plus the other registers such as accumulator, prog. counter, etcetera). No subroutines. It was the shape and size of the luggage space of a Hillman Imp (British car of the time), as that's where HCP built it. It was modular, using transistors - I believe he actually got the fourth form [tenth grade I think] one year to make the modules. I can still remember the opcodes: Z clear accumulator A address add the contents of address to accumulator S address subtract the contents of address from accumulator T address transfer accumulator to address I address stop for input (which went into address) J address jump to address+1 K address conditional jump (if negative IIRR) to address+1 E stop Note that Z and E - 000 and 111 - had no parameter; a wily programmer used those to store constants. Mr. Parr produced a booklet, including some exercises; they started with simple things like 3a+b (Z, A15, A15, A15, A14, E) and running totals (I15, A15, J15), but leading up to the 50th example which was IIRR calculate the highest common factor of two numbers (which I never managed). http://forum.6502.org/download/file....7446aed16b6825 d2bb7c5999023c http://forum.6502.org/viewtopic.php?f=3&t=2333 -- J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf Q. How much is 2 + 2? A. Thank you so much for asking your question. Are you still having this problem? I'll be delighted to help you. Please restate the problem twice and include your Windows version along with all error logs. - Mayayana in alt.windows7.general, 2018-11-1 |
#8
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What is the absolute smallest instruction set do you need to make a working computer?
Yousuf Khan 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_in...n_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. |
#9
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What is the absolute smallest instruction set do you need to makea working computer?
On 9/22/2019 2:26 AM, VanguardLH wrote:
https://en.wikipedia.org/wiki/One_in...n_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. Maybe, maybe not. It may not have been anything more than a curiosity in the 50's. Back then memory was very slow, and the caching technologies that have evolved over the decades was not available yet back then. So back then you had to make sure you explicitly put everything into registers. But these days, with your typical x86 machine being really a RISC processor emulating a CISC processor, and they've come up with so many automatic caching techniques that registers are no longer needed, and you can really work directly on memory without any performance penalties nowadays. Yousuf Khan |
#10
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What is the absolute smallest instruction set do you need to make a working computer?
VanguardLH on Sun, 22 Sep 2019 01:26:19 -0500 typed in
alt.windows7.general the following: Yousuf Khan 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_in...n_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. 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. -- pyotr filipivich Next month's Panel: Graft - Boon or blessing? |
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