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Y86 ISA Simulator in Java

This Java program tries to simulate a simplified version of the Y86 Instruction Set Architechture in a simple graphical interface.

Demo Program

Running the simulation

To run the simulation, open a terminal window and make sure you are in the project's directory then use java Simulation to open the GUI. Refer to README.TXT for more instructions on configuring the simulation.

You are welcome to try it and if there is a problem, please contact me or make a new issue.


  • This software should not have any dependencies other than the standard Java libraries and Swing.
  • Please review the README files for further instructions
  • To visualize class relationships please use BlueJ

Provided Demo Program

The built-in demo program consists of the implementation of for loop that increments a counter and writes it to a memory location (0x7C) until the counter is equal to 5. The program demonstrates most implemented Y86 instructions such as mrmovq, rrmovq, irmovq, addq, jmp and jge (conditional jump). The demo program also makes use of the call, return (ret) and halt instructions to demonstrate the memory stack implementation. The program is hard-coded in and is written to memory through byte arrays.

public void writeDemoProgram() {
  // pos 0
  // irmovq 0xCC, %rbp
  machine.mainMem.write(0, new byte[]{0x30, 0x01, 0x00, (byte) 0xCC});
  // rrmovq %rbp, %rsp
  machine.mainMem.write(4, new byte[]{0x20, 0x10, 0x00, (byte) 0x00});
  // call 0x14
  machine.mainMem.write(8, new byte[]{(byte)0x80, 0x00, 0x00, (byte) 0x14});
  // halt
  machine.mainMem.write(16, new byte[]{0x00, 0x00, 0x00, 0x00});
  // irmovq 0x01, %r2
  machine.mainMem.write(20, new byte[]{0x30, 0x02, (byte) 0x00, (byte) 0x01});
  // rrmovq %r2, %r3
  machine.mainMem.write(24, new byte[]{0x20, 0x23, 0x00, 0x00});
  // addq %r2, %r3
  machine.mainMem.write(28, new byte[]{0x60, 0x23, 0x00, 0x00});
  // irmovq 0x7C, %r4
  machine.mainMem.write(32, new byte[]{0x30, 0x04, 0x00, (byte) 0x7C});
  // rmmovq %r3, (%r4)
  machine.mainMem.write(36, new byte[]{0x40, 0x34, 0x00, 0x00});
  // irmovq 0xA, %r5
  machine.mainMem.write(40, new byte[]{0x30, 0x05, 0x00, (byte) 0x05});
  // subq %r3, %r5
  machine.mainMem.write(44, new byte[]{0x61, 0x35, 0x00, 0x00});
  // jge 0x38
  machine.mainMem.write(48, new byte[]{0x75, 0x00, 0x00, 0x38});
  // jmp 0x08
  machine.mainMem.write(52, new byte[]{0x70, 0x00, 0x00, 0x1C});
  // ret
  machine.mainMem.write(56, new byte[]{(byte)0x90, 0x00, 0x00, 0x00});


Email: wassgha(AT)


Simple Y86 Processor Simulator with custom low-level RTN definitions of instructions



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