The AVR/Z80 Hybrid boards arrived yesterday. Excellent service as always from Hackvana, my preferred fabricator. I set about constructing the first board. I’ve not included the output port on the first one since I haven’t got the two relevant 74′ chips in stock but they are on order and not necessary for initial testing.
It went together pretty easily. I soldered the chip sockets first, then the capacitors and then followed with the rest of the components. The Z80 is an original Zilog chip, one of a few I own. Before inserting the AVR, Z80 & AMIC SRAM, I tested the 7404 oscillator and all was well. I then plugged in the AVR and tested it by loading the standard ‘Blink’ program via ICSP, OK so far. I added the Z80, still OK and then the SRAM – Ooops! Dead short (indicated by my PSU going into Constant Current). After a quizzical few moments I realised I had plugged it in backwards! Doh! Luckily, I have a number of this chip if this one has failed but I reversed it and all is well.
I have started writing some test code which I will publish when complete and working. At the moment, the code is getting the AVR ports set up for sending data over to the SRAM. I’m currently working out the best way to convert a Hex or Bin file into something that the Arduino IDE will accept as data in preparation for sending byte by byte over to the SRAM.