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
The Parallel port has now been redesign, getting made right now.
Used level shifters with a extra output current.
This should work a bit better than last buld
I did not do much research on the TXB0108 series of level shifters, the output pins do not have enough drive to switch a Parallel port with pull up resistors with 1K on the WICE, My bad, a redesign is on the way.
I did quick PCB in KiCAD, Using Parallax Flip PCB. With some level shifters going to DB 25 Printer connector.
I am really like these Flip board for making prototypes easy. Depending on the circuit you can utilise the power coming from the USB. Also have access to 3.3V.
The design for this PCB can be found on my bitbucket on this project page.
Only spent a couple hours this part and look like very simple glue logic. Only difficult section was the compare logic done earlier.
I think I am going to need to test this, by designing some logic equations and put it into a PAL Assembler. Now I wonder where I can get a PAL Assembler now days.
Going through my stock of old part in garage. I found a tube PALCE22V10, now how do we program the little chippies.
Need to dig out that old Universal Programmer I packed away in a box.
I have setup a 1Hz clock signal to pin 1 to see what output pin are latched.
Then toggled the input on the Static I/O screen to see what changes and signals that changed on the clock edge.
I have been focusing on Pin 17 it looks like a select pin that is latched externally and seems to only change by pins 3,4 and 6. Also by the links on pin 7,8 and 10. I am thinking its compares the links with 3,4 and 6. Odd thing pin 5 and pin 9 do not have any effect, but is included in circuit. Picture below is quick circuit of Pin 17 output.
The re-engineered circuit shows the PAL has 15 physical inputs and 7 outputs. It looks like some of the outputs of the device are configured as inputs.
Setup Power for the PAL and the Level shifters.
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.