Hello all,

I've been researching "One Instruction Set Computers" (OISC/URISC http://en.wikipedia.org/wiki/One_instruction_set_computer) because I wish to build as simple a CPU that I can, although I still have much more to learn about circuitry before I begin such a challenge.

As far as I have been able to reason, OISCs are the simplest form of CPUs, in regards to hardware, while still maintaining Turing-completeness and the ability to be externally reprogrammed.

One such class of OISC is "Arithmetic Based Turing-Complete Machines", and one command that the wiki describes is "subtract and branch if negative". The page gives a couple of examples of higher level commands created by a sequence of this base level command and states that many other high level commands can be created from it as well. (The wiki states that "this class is universal and Turing-complete in its abstract representation", which confuses me, so I could be incorrect about some of this information.)

Is there any such place I could look to find a list of higher level commands that can be created from this simple one?

Thank you.

 

This is a good place to start for the synthesized instructions. aka higher level

http://en.wikipedia.org/wiki/One_instruction_set_computer#Synthesized_instructions

I would think that when they abstract representation they are simply talking about the system in the abstract. aka in theory as opposed to any given implementation.

If you do build this processor please post about it.

HTH