for a while now, i’ve been slowly working on building my own 8-bit computer. a big part of why i started this blog was to be able to chronicle my progress and share my successes and failures on that project.
as an opener, i think i should give some general background on the project…beware, things are about to get a bit technical. i think i will probably make some additional posts as well to discuss specific items in greater detail.
i’ve chosen to use the 65C02 as my CPU for this project for a number of reasons. probably the main reason is because the first computer i ever owned was an apple //e. when i was in high school in the late ’80s, i started to teach myself assembly language on the apple. however, college intervened and i never had the time to fully learn assembler. so now i have that chance, as all of the firmware for my computer will be written purely in assembler.
i currently have 4 or 5 apple //e’s in my collection (including my original one, still running strong after many years in storage). one thing i’ve always liked about the apple is its expandability – pop off the top and you’ve got a whole mess of expansion slots available. this makes prototyping and developing the system much easier – to start with, i’m simply piggybacking off the apple via an expansion slot, using its CPU and memory to test other elements of hardware and my software to control them. only when it becomes absolutely necessary will i move off on to my own dedicated hardware.
in this manner i’ve already completed the hardware and software design for a couple of major subsystems: the LCD and keyboard. i also have enough of a firmware shell complete to be able to run using solely my keyboard and LCD and not using any of the apple’s firmware code. a few basic commands have been implemented, with more to come.
i think that’s enough for a general overview…more to come in other posts.