Nice work. I need to dump the ROM for a piece of HP test gear that also uses a 3780 and this will save me a lot of time. I was also looking to replicate Sean's circuit. Thanks for sharing
Thanks. I'd offer a PCB but it needs a modification for level shifters as I said in the video. It's probably easier to have new PCs made with that mod on it. I'll see if I added the mods to the schematic
Interesting, I always thought there was no way to dump a mask rom, I wonder if it will also work with a NEC D650 uP as those have the test pin and mask rom and are used in a lot of equipment.
Mask ROMs are harder to dump as they are embedded in the microcontroller, but you can decap and dump that way, or use some form of test hardware type method. It looks like the D650 has been dumped, or a similar chip, here: www.handheldmuseum.com/forum/viewtopic.php?p=11037&highlight=
Hi, I’m trying to reproduce your circuit but i can’t find in your Github the schematic for the level shifter. You talk about some fet transistors… Thanks for what you are doing
Hello, yes I didn't have level shifters on my PCB, it is a mistake. I added Si23xx n channel FETs (one I had available) as simple inverting level shifters from the Pico outputs.
I think the code uses my level shifter and that inverts, so if yours doesn't then that might be a problem. Have a look at the code and see if you need to swap the polarity of the signals.@@RiccardoPietroni
