Added the PROM Programmer the the file list

A project log for Weird CPU

A minimal 8 bit TTL CPU using 1970s technology

agpcooperagp.cooper 07/29/2016 at 13:480 Comments

PROM Programmer

One of the sub-projects was to program the PROMs with the Monitor Code. Now I know some guys use a few switches, a power supply and a couple of fly wires! Well some of the schematics were not that much better. But today we have the Arduino so really it is pretty easy. A switchable power supply and some code.

Here is my PROM Programmer:

The only hard bit is making sure you wire it up correctly. Note the wire colours, same a the resistor codes, so wire 1 is brow, wire 2 is red etc.

Here is the board design:

You will see two 7805 voltage regulators. One is just a 5v supply and the other switches between 5v and 12.5v (the voltage pulse generator).

Here is the schematic for the voltage pulse generator (note the load resistors are the PROM loads for the simulation):

The PROM specifications are quite onerous with regard to voltage slew rate and load impedance thus the fairly complicated circuit.

I also note from the board design that I added data read circuity (the 1n4148 diode and 4k7 resistor).

I have also added the Arduino code for writing the high and low nimbles for the PROM Programmer to my file download list.