gordo@athena.mit.edu (Garet G Nenninger) (04/15/88)
I'm working on a small (VERY small) microcomputer control board to do things like convert morse code and RTTY to RS-232 serial as well as FAX to printer codes. Yes, I do realize that such devices are commercially available, but it seems more fun this way. I currently use a $30 VIC-20 to do these (well, not the fax). Anyway, it looks something like: 6502 microprocessor 8 K RAM/ROM (I'll probably use a battery-backed RAM cartridge that would be used for both the program and data storage. It would be mapped at both $0000 hex (for page-0 addressing ops and stack use) as well as at the top 8K of memory (for reset vectors)) 6522 VIA for printer output, demodulator input, timer one LSTTL IC to decode the memory (probably a quad XOR; it works out well for the ghost image of the RAM at the top of memory.) Anyway, right now I'm looking at using a crystal clock oscillator instead of a crystal and some gates. However, I've seen it hinted that you can hook a crystal directly to the 6502 and get it to oscillate. Does anyone have anything on this; I have never seen anything concrete?