Thread: What is the absolute smallest instruction set do you need to make aworking computer?
View Single Post
  #5  
Old September 22nd 19, 05:46 AM posted to alt.comp.os.windows-10,alt.windows7.general,comp.sys.ibm.pc.hardware.chips,comp.sys.intel,alt.comp.hardware.amd.x86-64
Yousuf Khan[_2_]
external usenet poster
  
Posts: 1,296
Default 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