Leap Electronics WICE-4M EPROM Emulator Reverse Engineered
Wiring diagram of the PIC Demo PCB interfaced to the WICE Parallel Port
Adobe Portable Document Format - 26.34 kB - 07/21/2017 at 13:55
PDF of the first version, schematic that was drawn in DesignSpark
Adobe Portable Document Format - 488.28 kB - 09/21/2016 at 04:31
Number of ways to Reverse Engineer a PALCE22V10.
Decided to remove the PAL from PCB and put on my "Electronics Explorer" from Digilent.
Wired in some level shifters so I can run and drive the PAL inputs at 5V.
The 10 output pins wired to lower 10 bits of EE Digital ports and 12 bit of the rest of EE Digital ports go to the inputs of PAL.
So now I can toggle each input and read the output to see what does what.
The WICE-4M has a PALCE22V10 on PCB some kind of "Glue Logic".
Attempted to read the device on a "Hi-Lo All-3A" Programmer, yep the security fuse is blown.
Looks like I will have to do this the hard way.
This project has slowed down, mainly concentrating on get the firmware working, no hardware design yet.
Need to boil up some more steam to get things moving.
Building the firmware in MPLABX
Everything is in 18F Assembly.
First started building MACRO's to make a data stack words.
So we have a kind of forth style words.
PIC 18 on the demo PCB is coming along very slowly.
I have created routine to Open WICE RAM A or RAM B for that 16 bit feature.
Then a routine to dump bytes to RAM when open.
Still need to work out how to do ROM profile setting on one of the latches.
A routine to Close off WICE RAM so as to allow access to external ROM interface.
Might start looking at designing PCB, thats if the MCU is still available.
Command's are send by latching data via the LINEFEED signal, establishing access to three other latches were STROBE signal pushes data for reading, resetting the address counter and setting ROM or RAM profiles. RAM writes via SELPTR signal. The address counter is incremented via the INIT signal.
I have been working on a schematic in KICAD I did not like DesignSpark version. I have living in the Linux Mint world since my Windows 10 machine for some reason stopped working. So if KICAD works on both platforms I will use that.
Started building firmware on my PICDEMO PCB to interface to the parallel port, communication via RS232 if successful will work on a USB interface.
And yes I maybe re-inventing the wheel here, it all about learning and personal achievements.
Software on is available bitbucket link below.
Decided to do a test run to see if the DIL Plugs work and to see if WICE-4M is still working.
First plugged WICE-4M into my Applix 1616 .
Handy box to sit WICE-4M.
Run an old PC with Parallel port, did want to remove XP so used a Megabuild of Dropbox.
Fired up WICE-4M, started up Dropbox, started up wice-4m software in Dropbox and it all worked.
Loaded memory with Applix 1616 OS ROM. Port A has even address and Port B has odd address send to WICE, Turned on the Applix 1616 and BOOM it started.
Now on to the next stage !!!
I started looking around for DIL Plugs that crimp or (splice) onto the ribbon cable, I found 28 Pin at Element 14 but I was really after 32 Pin. Just have to live with the 28 Pins for now might look at making PCB's next time or when I am desperate.