I've been playing with breadboards and PCBs again, and have a new little system available based on our favourite processor, the TMS 9900. Specs are:
- 16-bit TMS 9900 microprocessor running at 3 MHz.
- TMS 9901 Programmable Systems Interface.
- 32K + 32K byte (two banks) EPROM, bank selectable through jumper or CRU output bit.
- 32K + 32K byte (two banks) battery-backed static RAM, bank selectable through CRU output bit.
- RS-232 serial port operating at 19200 Baud (7 data bits, even parity, 2 stop bits).
- Single +5V @ 200mA power supply requirement.
- Reset switch.
- Small prototyping area on PCB.
Runs a system monitor, Cortex BASIC and Forth. No means of saving programs, but you can maintain/edit them on the PC and download them over the serial link. On the PCB, there are take-off points for all the main signals, if you want to expand it further. More details here: http://www.stuartcon..._breadboard.htm.
I've got a couple of bare PCBs spare - anyone interested? £27 each plus postage to you from the UK. This will include:
- The PCB.
- A TMS9900, 9901, 9904. I was given several sets of these, so am passing them on for free. Some parts appear to be “remanufactured in China”, but I’ve tested them and they seem OK (at least in the short term).
- +12V converter module.
- 64-pin turned pin IC socket.
- 3.3uH choke.
- Reset switch, power socket, pin strips.
- Various resistors where I have lots of spares.
All the other parts needed are easily available.
Let me know if interested.