bitfixer
Veteran Member
Hello to the Apple II folks here,
I wanted to introduce a device I've been working on fairly recently,
It's called the ROMulator, and it is a fully programmable RAM and ROM replacement board as well as a debug aid for 6502 based computers.
This originally came about as a tool for Commodore PETs, but it works for 6502 machines in general including the Apple II. I've used it recently to help debug some faults on a II+, have not finished that repair yet but it was able to quickly tell me that a certain address line was stuck when reading from RAM. Currently the machine will start with the RAM and ROM replaced with the ROMulator's onboard ram. It will run standalone in this mode, and in addition if you connect a raspberry pi to it, you can halt the CPU at any point and dump the contents of the ROMulator's memory. This is useful for debugging a system with bad video ram, for instance, since you can still 'see' the screen by looking at the memory in the video ram space.
There are switches to select between 16 different ROM sets or memory configurations. The contents of the ROMs as well as the details of the individual configurations is programmable using an external raspberry pi.
Segments of memory space with minimum size 256 bytes can be programmed to replace RAM (read/write), replace ROM (read only), duplicate writes to onboard memory but continue to read from the main board (writethrough), and pass through.
I wanted to introduce this board to the Apple II group here as an option when looking for tools to fix faulty machines. It can also be used as a standalone RAM/ROM replacement for as long as it's needed.
More information is here: https://bitfixer.com/romulator
Please let me know if you have any questions, thanks!
I wanted to introduce a device I've been working on fairly recently,
It's called the ROMulator, and it is a fully programmable RAM and ROM replacement board as well as a debug aid for 6502 based computers.
This originally came about as a tool for Commodore PETs, but it works for 6502 machines in general including the Apple II. I've used it recently to help debug some faults on a II+, have not finished that repair yet but it was able to quickly tell me that a certain address line was stuck when reading from RAM. Currently the machine will start with the RAM and ROM replaced with the ROMulator's onboard ram. It will run standalone in this mode, and in addition if you connect a raspberry pi to it, you can halt the CPU at any point and dump the contents of the ROMulator's memory. This is useful for debugging a system with bad video ram, for instance, since you can still 'see' the screen by looking at the memory in the video ram space.
There are switches to select between 16 different ROM sets or memory configurations. The contents of the ROMs as well as the details of the individual configurations is programmable using an external raspberry pi.
Segments of memory space with minimum size 256 bytes can be programmed to replace RAM (read/write), replace ROM (read only), duplicate writes to onboard memory but continue to read from the main board (writethrough), and pass through.
I wanted to introduce this board to the Apple II group here as an option when looking for tools to fix faulty machines. It can also be used as a standalone RAM/ROM replacement for as long as it's needed.
More information is here: https://bitfixer.com/romulator
Please let me know if you have any questions, thanks!