URM

Unlimited Register Machine (link).

A particular type of theoretical computer, with infinitely many memory cells, called registers, and formal rules to determine the machine's behavior based on their contents.

Commands

There are only 4 commands:

• Zero: Z x
• Successor: S x
• Transfer: T x y
• Jump: J x y l

Example commands

1. Set to zero value of register (R1).

Z 1

2. Add 1 (R1).

S 1

3. Copy a value from R1 to R2.

T 1 2

4. If R1 = R2, then go to line 999.

J 1 2 999

Example program

This program calculates the sum of two numbers (R1 and R2). The result will be stored in R1.

Z 3
J 2 3 999
S 1
S 3
J 1 1 2