I have mentioned previously some people who have done unbelievable things in computing, often in their spare time.

• Steve Wozniak designed the Apple and Apple ][, both the hardware and the software
• Maciej Szyc developed an emulator for the Cosmac Elf
• Ben Eater created a computer using chips and breadboards
• Bill Buzbee did both the hardware AND the software for a real computer using TTL chips

But these four guys did something else that is completely unbelievable: Barry Silverman, Brian Silverman, Ed Spittles, and Greg James wrote an emulator for a 6502 which does not depend on a manual of opcodes. They actually dismantled a 6502 to find out exactly how it was constructed.

Then they wrote a visual emulator which reproduces the work which the basic components (3500+ transistors) are doing.

This emulator does not emulate what the 6502 is supposed to be doing. It emulates what the 6502 is actually doing!

It’s an amazing achievement. The emulator can correctly emulate undocumented opcodes because it is doing what the basic components would be doing!

Now that they have conquered the 6502 they have started looking at other chips.

You can access their website here.

And here is a video where Michael Steil give a very good explanation of what the team did and how they did it:

I mentioned in a previous post that Ben Eater has a brilliant series of videos on building a computer from scratch.

He had a new series which is very good on building a computer using a 6502 microprocessor.

This is the microprocessor that I know best as it was in my Apple ][ and in my Atari 800.

Here is a link to his website where you can watch the videos (there are eight as I wrote this) and also buy the kit from him.

Here is the first video in the series: