vm

About

Simulating a physical computer by implementing a simple, register-based virtual machine in Go

The Computer

• 20 bytes of memory
• 3 registers: A pointer counter and 2 general purpose registers
• 5 instructions

Memory

• Simulated by a fixed sized array to model memory
• 20 byte capacity

00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
INSTRUCTIONS ---------------------------^ OUT-^ IN-1^ IN-2^

Instruction

The first 13 bytes are reserved for instructions for executing the program

Byte value mapping

halt    0x01
load    0x02
store   0x03
add     0x04
sub     0x05

Paramaters

halt 
load reg (addr)     # Load value at given address into register
store reg (addr)    # Store the value in register at the given address
add reg1 reg2       # Add reg1 and reg2 and store result into reg1
sub reg1 reg2       # Subtract reg2 from reg1 and store result into reg1

Registers

• 1 for the program counter
• 2 general purpose registers

Special thanks to invaluable lessons by Bradfield School of Computer Science