MOS digital simulations using Lua

Overview

The chip tracing software simulation mode can be extended using Lua scripts.

With Lua scripts it is possible to:

Read or write signals from the simulator.
Find any signal location with only a component name.
Control the simulator.
Create user interfaces to intuitively control the behavior of the script.
And more, by using the full potential of the exposed APIs.

Getting started

Scripts have to be placed in the folder ‘scripts/simulation/’.

To select a script and launch the simulation mode, press (Ctrl) + F1.
Its path will be memorized by the sofware (even if you close it).
Then you can quickly launch the simulation using the memorized script with (Shift) + F1.

Controls:

F1: Launch simulation.
(Control) + F1: Select script and launch simulation with Lua.
(Shift) + F1: Quickly launch simulation with Lua.
Note: It will use the previously selected script.

Making scripts

Simulation scripts are simple tables with at least some callback functions:

callback_create: will be called at start of the simulation.
Used mainly to initialise variables and find nodes.
callback_update: the update loop of the simulation mode.
Used to control the simulator by sending signals, update UI, etc…

Here a basic template:

local sim = {
    timer = 0
}

function sim.callback_create(editor)
    -- initialize inputs
    local proxy = editor:proxy()
    for i=0, proxy:inputsCount()-1 do
        proxy:writeInput(i, false)
    end
    proxy:simulate()
    
    sim.timer = 0
    sim.timer_max = 10
end

function sim.callback_update(editor, dt)
    if(sim.wait(dt)) then
        return
    end
    
    local proxy = editor:proxy()
    -- place signal updates here
    proxy:simulate()
end

function sim.wait(dt)
    sim.timer = sim.timer - dt
    if(sim.timer > 0) then
        return true
    end
    sim.timer = sim.timer_max
    return false
end

return sim

Intel 4004 CPU demo

This demo allows you to simulate the intel 4004 at a transistor level with an emulated rom (Intel 4001).

Limitations: No RAM, no I/O expanders (4003), only the 4004 CPU and an emulated rom.

Screenshot of the running simulation.
Focus on the registers and their content.

Features:

Initialization sequence to boot the 4004.
Intel 4001 emulation to run programs.
A simple UI to control the simulation.
Registers are read directly from the circuit in realtime.

Downloads:

Usage: Put the lua file in scripts/simulation/ and the save.json file in the program folder.

Public API

ImGui

Todo

onidev