Pointer machine

This instruction serves the same purpose as the if command in any imperative programming language.

Knuth noted that the SMM model coincides with a type of "linking automaton" briefly explained in volume one of The Art of Computer Programming.

Since outgoing pointers must be labeled by distinct symbols of the alphabet, both KUM and SMM graphs have O(1) outdegree.

This addresses some concerns for physical (as opposite to purely informational) realism.

There are other, minor differences between the models, such as the form of the program - a state table instead of a list of instructions.

Use of the model in complexity theory: van Emde Boas (1990) expresses concern that this form of abstract model is: Gurevich also expresses concern: Schönhage demonstrates the real-time equivalences of two types of random-access machine with the SMM.

Some steps in the execution of a 2-symbol {0,1} machine with instructions: (1) new ε; (2) new 1; (3) new 11. Instruction #1 initializes the storage graph as a single node, node 1, in the storage graph.
Evolution of the storage graph in a 2-symbol {0,1} machine with instructions: (1) new ε; (2) new 1; (3) new 11; (4) new 10; (5) set 111 to 10. At this time, if the machine were to do the if 10=111 then xxx, then the test would be successful and the machine would indeed jump to xxx.