Wednesday, November 25, 2015

Update on MKHBC-R1, 6502 based home-brew computer: UART - finished!

I finished assembling the UART card. At this time I test the system outside of the mother-board. I also added (temporarily) ZIF sockets to CPU card for EPROM (since the system is still in development, this will be very useful) and for CPU. You may be wondering why did I have a need to have a ZIF socket for a CPU? Well, some time ago I bought from e-bay a lot of eighteen R6502P chips very cheap. I have never had a chance to test them. Now came their time. I dropped each in the ZIF socket and tested them in my system. All worked fine, so future looks bright for any new 6502 based projects.
I've published a short demo on youtube of my working system.

Working system with one of R6502P CPU-s I've been testing in the ZIF socket and CPU speed jumper set to 0.9 MHz (my standard configuration is R6502AP with 1.8 MHz clock). The voltage is a bit low here (4.6V). I improved the connections a little bit and later got 4.8V, a bit more acceptable and within tolerance.
I use my port of Meadow Operating System (which is really a monitor program working over serial port) to control the system, upload and run programs on it. Above - Tiny BASIC is being uploaded to RAM.
Tiny BASIC uploaded and running. Time to play some game. Euphoria is a small kingdom simulator written in Tiny BASIC.
Lot of 18 6502 CPU-s.