I wanted to design and build a computer that’s based around the 6502 microprocessor. When I say build a 6502 computer, I mean a computer that has been built from scratch! When people say that they have built a PC, what they have done is put together circuits and peripherals. To me, truly building a computer is building with discrete components, ICs, wires etc. I hope that by following this project, people will find it of interest, learn something and that some will want to build their own.
For a computer to be useful, it needs to be able to store and run programs. Once the computer is at this stage, I want to then write programs in assembly. You don’t have to know 6502 assembly to understand the contents of this course but I encourage you to learn about it, as it will cement your understanding of many important concepts. I have a course on 6502 assembly language.
There are a number of prefixes that I will be using throughout, these are shown in Table 1, with their meaning.
| PREFIX | MEANING | EXAMPLE |
|---|---|---|
| # | decimal value | #22 |
| #% | binary value | #%10010110 |
| #$ | hexadecimal value | #$EE |
| #’ ‘ | ASCII value | #’B’ |
| memory address in decimal | 1001 | |
| $ | memory address in hexadecimal | $1101 |
Each section of the computer could be made with a multitude of different components. However, with my design, there is a stipulation that I would like to make – that the ICs are of the era of the 6502. The 6502 was introduced in 1975 and I have decided that ICs will be used in my design if they were introduced in the 70s.
For each of the images that I have created, you can click on them to see an enlarged version, on a separate page.