SUBS Machine

Van der Poel postulated a computer with only one instruction. Fifty years ago mainframe computers had 100 to 200 hard-wired instructions. RISC computers came along with fewer instructions.

But a computer with only one instruction? How useful could that be?

It turns out to be supremely useful on several fronts:-

(1) If memory is cheap, you can build a functioning microcomputer from parts ordered through the DEC handbook, using NAND/NOR gates and the like.

(2) You can build an interpreter that takes in a hybrid language of APL and FORTRAN and spits out a program that can be run on the SUBS machine. It follows that since you can simulate the SUBS machine in FORTRAN, you can run this single-instruction simulation on the single-instruction computer itself.

(3) Learn essential skills in the design and development of macros.

(4) Learn essential skills in the design and development of libraries of code.

(5) Learn why top-down program design is important.

(6) Learn why bottom-up program coding is important.

(7) Learn what self-testing procedures are and how they can cut your program development time in half.

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