About

Here's the simulator itself, written entirely in Javascript and with thanks to Martin Maly and Chris Double for their 8080.js Intel 8080 emulator. To use, it's identical to getting your pre-assembled MITS Altair shipped from New Mexico, opening the box and plugging it in. So read the ALTAIR manuals for info on what the switches do, and read the 8080 instruction set reference for info on the machine language. Important things to know: 1. First turn it on 2. There's a slide-out at the bottom which will let you "see inside" the processor and inspect registers and memory. This does not exist on real Altairs. Click here to LAUNCH SIMULATOR With thanks for Gary Graham for this image What you can do The Intel 8080 is a "Turing Complete" machine, which means anything that any computer can do, a MITS Altair can do too (subject to memory limitations). In reality, here's a couple of sample goals you could set yourself: A program that adds two numbers, say 3 and 7, and displays the result on the LEDs A program that reads the switches, and in the LEDs displays the same pattern A program that starts at zero and displays a binary count in the LEDs A single LED on, all the others off, and the active LED sliding up and down the display, over and over You'd start by reading the original Altair manual (slow to load), which explains everything from the very start in good detail. Understand what the switches do, understand the Intel 8080 instruction set, and get coding. Or for something much easier on the eye, Kevin Cole's reformatted version of the same manual. Known differences There's a few areas in which the simulation is not completely accurate: Single-step on the Altair operated on a per-cycle level, whereas the simulator operates per-instruction. This is a characteristic of the 8080 library being used. The updating of the LEDs and reading of the switches is not as speedy or as immediate. This is because the HTML DOM is a lot slower than actual pieces of wire. Some of the status LEDs are not faithfully simulated. The Protect switch is not implemented.