You can compare the cartridges to load ROM images you have programmed in a computer, for testing purposes, or for running backup/homebrew games without having to make a new cartridge. You can compare what features you find most useful, number of pins, number of included features, etc.
The features I would find useful are:
The features I would find useful are:
- 60-pins cartridge (it might be nice to offer both versions, although the things listed below might not work if you have NES and cannot use a keyboard; therefore the 72-pins version would have to be different)
- CF cards
- The file format doesn't matter too much, as long as it is fully documented
- Made of open source software, and open source (or fully documented) hardware
- Built-in ROM of Forth or BASIC interpreter or whatever, to use with Famicom keyboard (and the built-in commands in the ROM may be used to load files from CF card) (possibly it might also help if you push START button it will load BOOT.ROM from a CF card, such as in case you don't have the keyboard)
- Charge switch (probably a physical switch), which when turned on, means you can load a program, turn off the console, turn back on the console in a few seconds and then it will start immediately (from the copy in RAM, which is charged while turned off for this purpose), so that you can properly test from power on state
- Possibly, bread board so that you can wire a mapper yourself, if the built-in mapper isn't good enough