Execution

Execution Cycle

1. Fetch the value from memory at the address of the instruction counter
2. Increment the instruction counter
3. Decode the instruction
4. Execute the instruction (e.g. halt, or store)
5. Repeat until halted

Simple and effective.

Execution Errors

• Invalid memory address - The address is not in the range (0 - 99).
• Invalid instruction - The instruction is not recognised.

Other Facts

• Memory is stored in a decimalised twos-complement (999 == -1, 998 == -2, ..., 500 == -500, 499 == 499, ..., 0 == 0)

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