Ceti Popcorn
Popcorn is a mostly-functional, mostly-complete multi-board MC68010-based computer system.
What does work?
- MC68010 CPU at 10 MHz
- 1 MB zero wait state Flash memory for boot code
- 1 MB zero wait state Static RAM for programs and data
- RS-232 serial port (boot code runs it at 38400, 8N1, hardware flow control)
- 8 TTL discrete inputs with optional DIP switches
- 8 TTL discrete outputs with optional LEDs
- Interrupts
- SPI Master port
- 555 periodic timer
I've tested the SPI master port, but my attempts blew out some part of Ceti I/O board serial number #1. So I'm labeling that "does not work" and on Ceti I/O #2, I didn't populate the shift register that was the basis for the circuit.
I've tested the 555 timer on CetiCPU #1, but it didn't appear to be ticking according to my logic analyzer. This is my first attempt at using a 555 timer and it seems I may have picked non-optimal passive component values. I later came across a neat 555 calculator site that has suggested some new component values. I'm thinking about building up CetiCPU #2 with different timer passives to see if that makes a difference. Would be pretty cool to have a periodic timer that would allow for a pre-emptively multitasking OS. Someone on HN suggested EmuTOS.
The Ceti I/O Board (schematics, gerbers):
The Ceti Memory Board (schematics, gerbers)