Schematics 2.2 are finalized.

I will add no new features to it. Compared to the 2.1 implementation, it will add:

  • a jumper based USB/RS232 multiplexer.
  • interrupt driven serial communications. Both HW and SW flow control will be supported.
  • a simplified (and fixed) JK flip-flop based CPU clock generator with possible support for clock stretching via signals provided over an extension connector.
  • a divide by three circuit in the ACIA clock generation path. Serial communications will be either at 38400 or 115200 bps.
  • simplified CompactFlash connectivity over an inexpensive ATA/CF adapter.

All I need to do now is to thoroughly verify the thing, come up with a realistic and detailed enough bill of material and send the outcome to Jean-Marc for an initial PCB batch. I am still missing components (IC sockets, resistor networks, straps, headers and capacitors) that will eventually be needed for the first PCB trials. Stay tuned!


 

Comments

Post a Comment

Popular posts from this blog

We Have a PCB Now!

Image
Flash News: my new hardware partner is a professional in the field of electronics. In less than two weeks, he produced a PCB design for the Z79Forth reference board in Kicad 6. The Gerber files will be sent to JLCPCB today. And they're giving me a wonderful potion 'Cause I cannot contain my emotion " Genesis, "Supper's Ready" (from "Foxtrot", 1972).
Read more
So when you consider yourself a designer, from a hardware perspective especially, you will have to make decisions that are not directly driven by your project's goals but rather by some production costs constraints. This is the voice of reason and it is what your boss wants to hear, obviously.   Z79Forth is not a professional product development effort in any modern way. It is a neo-retro endeavor. What this means is that I stayed away from contemporary packaging technology--namely SMT, which I think is not to be considered in scope for the amateur market. Deliberate choices were made at various points in time during the hardware development phase of the project. I think a few of them are worth elaborating on: use of through-hole only TI's HCT technology. This will get you TTL level compatible inputs, CMOS level compatible outputs and low power consumption, the whole thing under adequate switching times for old times' clock frequencies. use of CXO integrated oscillators. Th...
Read more
 Z79Forth is a project that originated with the revival of hardware design for practically anyone interested in the field. The Arduino project was instrumental and I did build from there and various embedded electronics experiments up to an ESP8266 based weather station. That device was programmed in LUA (an interpreted/compiled language designed by PetroBras) and still lives on in the lab. It worked as a battery operated device for about a month in the field, i.e. below my rooftop, and demonstrated a very tangible reality: power management is the last thing a designer wants to think about but it is essential. I ended up re-focusing the project on that particular aspect of the system, using NiMH rechargeable batteries and a solar panel. Under favorable weather conditions (southern exposure of the solar panel), I estimate that the device should be able to work for as long as the batteries will recharge--about three years. However, I have yet to confront this with reality so this rem...
Read more