I designed the CSC258 computer for teaching the basics of computer design. Real processors have way too many details that do not illustrate any important principles of computer design, but they have to be learned in order to write programs in their language. So I designed a simple, basic computer whose machine language is easily learned, and I can show all the processor circuits in complete detail.
Here is the assembly language.
Here is the assembler and simulator written in C.
Here is the executable.
Here is a warning concerning its operation.
Here are the circuit diagrams.
Here is a little assembler program to try, if you like.
And here is a function to print an integer and a function to print a string.