I have been following Veronica, a 6502 based computer being built by Quinn Dunki over at Blondihacks since the projects beginning in late 2011. Recently when sorting through my stock of collected parts I realized had almost all of the the required parts on hand.
Whenever people talk about what they learned to program on it tends to come back to a few main chips, namely the 6502,z80 and the 6800. The z80 took my interest, partly because I liked the challenge of having less information and compilers to rely on, partly because I liked the IO input/output system it used but mostly purely because I had one that I believed worked.
Now I have never worked with any CPU’s of this vintage.. Well any CPU’s by themselves at all really, mostly just microcontrollers and common computers, so this is probably going to be a long project of errors but thats what this blog is for really.
System design, I am deviating already from most other builds and ignoring the backplane approach and instead melding it with the Arduino approach of shields. So my strange concoction of the two is a stackable header set on the top and bottom, and corners that carry the signals. This basically builds us a vertically stacking backplane that will allow me to form my boards into a cube of sorts. The goal design for the project is a roughly 5cmx5cmx5cm cube shape formed from a stack of 5 boards.
I decided I should do this all totally wrong and start by doing a rough design of the main boards in the system, and then test the parts as I install them.
The rough specs for the system are :
- 64K of Shared SRAM/Code space
- 4 I/O ports
- LCD (16x2) for status display
- Blinky lights
- Powered via USB
- UART for outside communication / Debugging