COMP1860 instruction-set simulator

based on Null&Lobur's MARIE instruction set

16-bit words · 4-bit opcode + 12-bit address · memory 0x100–0x120 · two's complement

Main memory

Addr

Hex

Binary

Dec

Instruction set

1	Load X	AC ← M[X]
2	Store X	M[X] ← AC
3	Add X	AC ← AC + M[X]
4	Subt X	AC ← AC − M[X]
5	Input	AC ← next value in the input queue
6	Output	display AC
7	Halt	stop execution
8	Skipcond	800: skip if AC>0 · 400: skip if AC=0 · 000: skip if AC<0
9	Jump X	PC ← X

Registers

next instruction

—

Next step

Fetch

Decode

Execute

Load a program, then press Step to fetch the instruction at 0x100.

Memory image

One word per line: 100 1104, or bare values loaded from 0x100 upwards. Values may be 4 hex digits or 16 binary digits. Use # or // for comments.

Input & output

Input queue (consumed by Input)

Output

—

Execution trace

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