https://github.com/brentseidel/sim-cpu

CPU Simulations written in Ada
https://github.com/brentseidel/sim-cpu

6502-emulation 68000 8080a 8085 ada assembly-language simulation z80-emulator

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CPU Simulations written in Ada

• Host: GitHub
• URL: https://github.com/brentseidel/sim-cpu
• Owner: BrentSeidel
• License: gpl-3.0
• Created: 2022-01-21T17:08:19.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2025-04-13T19:23:10.000Z (2 months ago)
• Last Synced: 2025-04-13T19:39:41.464Z (2 months ago)
• Topics: 6502-emulation, 68000, 8080a, 8085, ada, assembly-language, simulation, z80-emulator
• Language: Ada
• Homepage:
• Size: 2.46 MB
• Stars: 10
• Watchers: 3
• Forks: 0
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Sim-CPU

CPU Simulations written in Ada

This is spun off of the Pi-Mainframe repository.  Moving simulation into

a separate repository will allow simulators to be developed more independently

as well as used in other applications.

[![Alire](https://img.shields.io/endpoint?url=https://alire.ada.dev/badges/bbs_simcpu.json)]

(https://alire.ada.dev/crates/bbs_simcpu.html)

[![Alire](https://img.shields.io/endpoint?url=https://alire.ada.dev/badges/simcpucli.json)]

(https://alire.ada.dev/crates/simcpucli.html)

[![Alire](https://img.shields.io/endpoint?url=https://alire.ada.dev/badges/loadcpm.json)]

(https://alire.ada.dev/crates/loadcpm.html)

## Implementation

The root of the simulators is the abstract object "simulator" defined in the

BBS.Sim_CPU package.  It defined the external interface that all simulators

must implement.  It is expected to evolve as some actual CPU simulators get

implemented.

## Simulators

The following simulators are implemented.

### Simple Example

This is not really a CPU simulator.  Its main purpose is to blink the lights

in the Pi-Mainframe in interesting patterns.

### Intel 8080

[More information](https://github.com/BrentSeidel/Sim-CPU/tree/main/src/i8080/README.md)

All 8080 and 8085 instructions have been implemented.  Z80 instructions are

being implemented, but are not ready for use yet.

### Motorola 68000

[More information](https://github.com/BrentSeidel/Sim-CPU/tree/main/src/m68000/README.md)

All the 68000 CPU instructions have been implemented.

## CLI

A command line interface is provided for development of both the simulators

and software that runs on the simulator.

The following commands are currently provided:

-  BREAK 

    -    Set a breakpoint (currently only one can be active at a time)

-  CONTINUE

    -    Continue execution

-  DEP  

    -    Deposit value to a memory location

-  DUMP 

    -    Display a region of memory

-  EXIT or QUIT

    -    EXIT the program

-  GO 

    -    Start execution at a specified address

-  LISP

    -    Enter Lisp interpreter

-  LOAD 

    -    Load data from a file into memory

-  REG

    -    Display register values

-  RUN

    -    Execute instructions until halt or breakpoint

-  STEP

    -    Execute one instruction

-  TRACE 

    -    Print information for each instruction executed

-  UNBREAK 

    -    Remove a breakpoint

### Lisp

For more information on the embedded [tiny-Lisp](https://github.com/BrentSeidel/Ada-Lisp)

interpreter.

The following additional Lisp words are implemented for controlling the

simulation.  With use, more words may be added.

-  Execute one instruction

    -  (sim-step)

-  Get/set memory (byte/word/long)

    -  (memb addr value)

    -  (memb addr)

    -  (memw addr value)

    -  (memw addr)

    -  (meml addr value)

    -  (meml addr)

-  Set execution address

    -  (go address)

-  Read register value (index is simulator dependent)

    -  (reg-val index)

-  Return number of registers

    -  (num-reg)

-  Return or set simulator halted state

    -  (halted state)

    -  (halted)