The Commodore 64 and the Commodore 128 uses the same method for editing code. You press enter over a line, and that line is stored the with the index of the entered line number, overwriting any existing code on that with that index. The Commodore 65 has the same machine code monitor as the Commodore 128 (it runs more smoothly because the C65 is much faster than the C128). Also, adding and overwriting Basic code is done in the same way. Editing is probably not, but I am not sure. On the C128, you just had to make sure you saw the line of code on screen, move the text cursor to it, write something else on top of what[…]

This is truly one of those machines you really want to own. The Commodore 65 (or C64DX) never made it to the market, probably because of the huge success of the Commodore Amiga. But what a machine it is. Better graphics than the Amiga, 128 Kb of RAM (could be expanded 8 Mb) and a Basic interpretator for Commodore Basic 10. Commodore Basic 10 is sort of the same that the Commodore 128 has (Commodore Basic 7) but well improved with added support for mouse programming and genlocking (that is adding graphics to video). The most amazing feature of the C65 must be that it had two SID chips for sound. This gave the machine 6 channels of fat analogue[…]