Reading HP67 ROMs

[teenix]

Hi all,

I got the PCB for the ROM reader today. It is not fully populated as I am verifying the board before soldering some ICs and I am still waiting on a couple of parts. The LED at lower right corner is flashing away so the PIC processor is running and has communication to the PC.

It is pretty simple but looks complicated due to the fact it can supply the voltages to read the ROMs directly or it can tap into the HP circuit board and use its inbuilt power supply. Most of the circuitry is for generating the phi1 and 2 signals plus the interface for the Is and Data busses. These can be bypassed with a switch (or plug links) when using the signals direct from the HP board and the PIC processor will then supply the system clock signal to the ACT.

There is a plug link to switch the Phi signals for +6V and -12V, or +6V and GND depending on the ROM being read, for example HP-67 or Spice. There are 2 sockets on the board for 8 pin ROMs and the 18 pin ROM 0 chip. There is also a connector for flying leads which can connect a ROM IC with different pin outs.

There is some software to write and some testing then should be done.

I also got the Spice boards today so will start dealing with that when I can.

cheers

Tony