Design Goals

I already have one 6502 based computer, the Replica I, but there isn't any fun in leaving it at that. I have plans in the works for two more single board computers (SBC), with the end goal of hopefully having the three communicate with each other for some useful function. Here are the proposed specs for each:

Replica I TE - Briel Computers
- 32KB Ram
- 8 KB ROM with BASIC, monitor and an assembler
- Slow video terminal i/o
- 1mhz


First computer - constructing breadboard iteration now, maybe PCB eventually.
- Name - suggestions?
- 8KB SRam on the breadboard, 32KB in a permanent version
- 8KB EEPROM with a monitor and BASIC
- Small ASCII LCD and fast serial RS232
- Selectable clock rate, 2mhz, 1mhz, 500khz
- MOS 6502 CPU
- R6522 I/O chip
- R6551 serial (if I can find one cheap, otherwise I may use one of a couple old UARTS I have)
- Several 74 series chips for address decoding, clock generation and division, and phi2 handling.


Second computer - enclosed in an old radio case, in the spirit of early micros
- Name - Pulsar Micro. Because of the blinkenlights :)
- W65C02S mpu for DMA compatibility
- Intel P2102 RAM chips. 8 add up to 1KB. Circa 1973
- No ROM
- 250khz or 500khz clock to allow the RAM to keep up. A simple card could speed it up for fast RAM.
- 24 switches and lights on a front panel to program data in one byte at a time in the spirit of     the Altair computers. Expansion cards can add ROM or I/O
- Built in linear power supply

This computer is basically a recreation of exactly the parts and specs an early hobbyist might get out of a home computer. This is exclusively for fun.



The replica I will be used for ROM burning and software development until I get computer 1 running.

One of my design philosophies with these older computers is avoiding programable glue, micro controllers, or other modern components that weren't available at the time. The exceptions are high density RAM chips and the newer WDC processors. Doing so detracts from the purity of the early micros, in my humble opinion.