A Mysterious 6502 Apple 2 Simulator

Nice, visual simulators of CPUs such as the 6502 are usually made much later and with more modern tooling than what they simulate. But what if that wasn’t the case? What if a simulator runs on the very hardware it’s simulating?

This is what [Tea Leaves] stumbled upon when he found a mysterious disk with only “APL6502.SIM” on it. [Tea Leaves] demonstrates the simulator with a basic 6502 assembly program, revealing an animated, beautiful Apple 2 simulator that actually runs on the Apple 2! The simulator shows all the major components of a 6502 and actually animates the complete data flow of an instruction.

But why is this mysterious? It’s mysterious because – a “hello” program aside – it’s the only thing on the disk! Not so much as a single clue as to where it came from. [Tea Leaves] finds out where it comes from, including incorrectly copied disk images and a revelation at the end.

Video after the break.

14 thoughts on “A Mysterious 6502 Apple 2 Simulator

        1. MECC was formed in 1971. Oregon Trail also came out in 1971, although originally on TIES (not sure when Oregon Trail appeared on MECC, probably 1975 timeframe). Since you mentioned that is after your time… when was your time?

  1. Immediately recognized this as the MECC 6502 simulator from the screenshot. Growing up in 70s-80s Minnesota, MECC was a godsend to the young hacker. They also produced a fairly nice 6502 assembler, if I recall correctly.

    And, of course, the little-known gem Oregon Trail.

  2. Yes I remember of this simulator from the 80s. As a teen learning the 6502 I was just as excited to see this as you were on this video. And it was definitely in the early 80s when I saw it. Thanks for bringing back memories!

  3. Destin’s Smarter Every Day youtube channel recently released a new video where they got into what makes a computer game a good game and in the entire process of inventing “fish game”, Destin located and interviewed the guy who wrote/spearheaded Oregon Trail…the MECC dude himself. It was a short interview, but still cool the guy is still with us.

  4. I love 6502. A small program written by a man named Bill Basham has been fascinating me for 40 years. It’s a program called Diversi-Dial. Back way before the internet was mainstream this chat program has brought together many people. Known as Dialers, Diversi-Dial was at the forefront of early communications systems. You can experience this today at ddial.com and magviz.ca. I’m normally on there chatting. I’d like to find a program that can actually take a 6502 disassembly and create a flowchart (remember those?) of that disassembly.

  5. Nerd-alert: There never was an “Apple 2”.

    There was an “Apple II”, which was stylized as “apple ][” (or “APPLE ][” on the upper-case-only screen). 🤓

    Always nice to get some information completely irrelevant to the article at hand, right? RIGHT? 😉

  6. The Locksmith 5 copy utility contained an emulator for not just the 6502 but also its disk subsystem, for the purpose of tracing the boot sequence of copy-protected software… all running on the Apple II.

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