I've posted about this on IRC and a little on here before switching host, but I thought I'd post a proper thread here as it seems to have got some GameDev members interested in Electronics.
I'm currently working on a Z80 computer built from electronic components soldered to stripboard, so not very high tech stuff. It's running the Z80 BBC BASIC, and has simple hardware specs:
- 10MHz Z80 CPU running at 2MHz.
- 128KB Flash ROM to store the OS.
- 32KB SRAM.
- 128x64 graphical monochrome LCD.
- Two PS/2 ports (keyboard and mouse).
- I2C bus to add further components.
- DS1307 real-time clock (I2C) for time-keeping functions.
I haven't worked out what I'm going to do for storage yet (I have some 32KB I
2C EEPROMs that may do the trick for removable storage, and they can be programmed externally for transferring files between a modern PC and this computer). The system only runs at 2MHz as the LCD requires at least 900nS when reading or writing data, and running the Z80 slowly seemed easier than designing a circuit that would force the Z80 to wait for a few extra clock cycles. I had planned on being able to switch between a 2MHz and a 10MHz clock by a multiplexer, but the changover from one signal to another is a bit noisy and generates several > 10MHz clock cycles which cause the system to crash.
More information and links to journal posts
here.
I'm hoping that maybe some other people may have an interest in building computers; it's really not tricky to do and is great fun! My reference is my A Level textbook,
Electronics Explained by M. W. Brimicombe. (You can preview the book on
Google Books).