Beginnings of a virtual 6502 mode for Gigatron

Marcel of the Gigatron TTL Computer Project has announced a work-in-progress 6502 emulator, “v6502”, residing in ROM. (This complements the existing virtual machine: one is not expected to program the Gigatron at machine level, although it’s possible.)

Here’s Wozmon running on the virtual 6502:

From this thread on and this thread on

Oh, and there’s an in-browser emulator, of this not-at-all-an-apple-1:

Online emulator here: Remember to type letters in UPPER case!


That’s a neat hack!
Fun stuff.

I decided to add the flashing @-cursor, map delete to rubout and all keys to uppercase. Much more authentic :slight_smile: . Interestingly, I could restore more of the original wozmon bytes along the way.


Hi All,

Marcel @marcelk has kindly shared a v4 ROM with me that contains the virtual 6502 code plus the 6502 WozMon and 6502 disassembler - as used on Apple 1.

I now need to take a crash-course in 6502 assembly language programming so that I can make full use of this whole new dimension to the Gigatron TTL Computer. :wink:

Also, this week, fellow Gigatron enthusiast xopr, has connected an Arduino to the Gigatron expansion pcb, using it as an SPI slave, which can be used as a general purpose GPIO peripheral processor. More details in this thread:

Upcoming Events:

If you are in the UK, I will be attending OSHcamp in Hebden Bridge on August 31st/ Sept 1st with a Gigatron presentation, and then with @marcelk at the Cambridge Centre for Computing History for their RetroComputer Festival on the 7th & 8th September.





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