Minicomputer Simulator

A Java/Swing simulator for the CSCI 6461 minicomputer architecture — a 16-bit machine with 4 general-purpose registers, 3 index registers, 2 floating-point registers, a small instruction set, memory-mapped I/O, vector and FPU support, and a software-managed trap table.

Originally built by "Team Yellow" for CSCI 6461 at GWU.

Requirements

• JDK 21 or newer (the Gradle build uses a Java 21 toolchain — Gradle will download one automatically if you don't have it).

That's it. The Gradle wrapper bootstraps everything else.

Build & run

From the project root:

# Linux / macOS
./gradlew run

# Windows (PowerShell or cmd)
.\gradlew.bat run

This compiles the sources, instruments the IntelliJ GUI form, and launches the Swing front panel.

To produce a runnable JAR:

./gradlew jar
# Output: build/libs/minicomputer-simulator.jar
# Must be run from the project root so the simulator can find ./static.
java -jar build/libs/minicomputer-simulator.jar

Using the simulator

The interface mimics a front-panel minicomputer console:

• IPL — Initial Program Load. Boots the ROM (trap table, fault handler, bootloader, and built-in subroutines like print-int, read-string).
• Load Program 1 / 2 — Assemble and load one of the bundled demo programs.
• Load Instruction Demo / Floating-Point Demo / Vector Demo — Quick demos for various instruction classes.
• Choose File then Load Program — Assemble an arbitrary .txt program from static/ (or anywhere on disk) into memory at a chosen address.
• SS — Single-step the next instruction.
• RUN — Execute until halt, fault, or I/O wait.
• HALT — Stop a running program.
• RESET — Wipe registers and memory.

The two consoles on the right are the operator console (program I/O — text that programs read/write via IN/OUT) and the field engineer console (simulator diagnostics).

The card-reader pane lets you load a "punched card" deck (a text file of newline-terminated records) for programs that read input via the card reader.

Source layout

src/com/simulator/awesome/   Simulator core + Swing UI
  Simulator.java               Top-level machine state (registers, subsystems)
  ControlUnit.java             Fetch/decode/execute loop
  Memory.java, Cache.java      Memory + cache
  ArithmeticLogicUnit.java     Integer ALU
  FloatingPointUnit.java       FPU
  *Instruction.java            Instruction-class implementations
  Assembler.java               Two-pass assembler for the .txt program format
  ReadOnlyMemory.java          Loads trap table and built-in routines on IPL
  InputOutput.java             Console keyboard/printer + card reader buffers
  Interface.java / .form       Swing front panel (IntelliJ GUI Designer)
  Main.java                    Entry point

static/                      Demo programs, ROM payloads, indicator-light PNGs

Build internals

The Swing UI is defined in Interface.form, an IntelliJ GUI Designer file that gets woven into Interface.class at compile time. The Gradle build delegates to IntelliJ's published java-compiler-ant-tasks (Javac2) to do the instrumentation, so the form keeps working without IntelliJ being installed.

License

No license has been declared. Treat as all rights reserved by the original authors unless they say otherwise.