8080js

Precise JavaScript emulation of Intel 8080 CPU

Based on BSD-licensed work by Copyright (C) 2008 Chris Double

All flags and instructions fixed to provide perfect compatibility with original "silicon" CPU.

This emulator passes the Exerciser http://www.idb.me.uk/sunhillow/8080.html

Big thanks to Roman Borik (http://pmd85.borik.net). His help lets me achieve such a perfect HW compatibility.

Used in all emulations at ASM80 online IDE

Usage

(a.k.a. The API)

• window.CPU8080 - main object (instantiated at the start - it shall change)
• CPU8080.init(memoryTo,memoryAt,ticker,portTo,portAt) - Initializes the whole system. All parameters are callback functions for port / memory access:
  • memoryTo(addr,value) - store byte to given address
  • memoryAt(addr) - read byte from given address
  • ticker(T) - unused. For future use
  • portTo(addr,value) - write byte to given port
  • portAt(addr) - read byte from given port
• CPU8080.T() - returns clock ticks count from last init (or reset)
• CPU8080.reset() - does a CPU reset
• CPU8080.set(register, value) - sets internal register (named PC, A, B, C, D, E, H, L, F, SP) to a given value
• CPU8080.status() - Returns a object {pc, a, b, c, d, e, h, l, f, sp} with actual state of internal registers
• CPU8080.steps(N) - Execute instructions as real CPU, which takes "no less than N" clock ticks.

Disassembler:

• window.CPUD8080 - main disassembler object (instantiated at the start - it shall change)
• CPUD8080.disasm(i,a,b) - Disassembly instruction. You have to provide 3 bytes - first one is an instruction code, second and third are parameters (they can be omitted when instruction is single byte or two bytes). It returns an array of two elements: the first is instruction mnemonics, the second is an instruction length.

You can use 8080js also as Node.js module.

Tests

Run the tests in Node.js (no dependencies, Node 20+) with npm test. It runs the basic tests (test/node/cpu8080.test.js) and the full CPU diagnostic – MICROCOSM ASSOCIATES 8080/8085 CPU DIAGNOSTIC VERSION 1.0 (test/node/cpudiag.test.js, program in test/fixtures/cpudiag.hex). The diagnostic test fails when the program reaches its error exit (0x06A5) or does not finish within 1,000,000 steps.

The browser version of the basic tests (qUnit + JSHint) is test/index.html. test/emu8080test.html runs the same CPU diagnostic manually in a browser (its inline hex must be kept identical to test/fixtures/cpudiag.hex).

Roadmap

• Change it from self-called constructor to real class

Support