Maybe a problem with VCC? Check the datasheet for your chip (different mfgs have different tolerances) and check your actual VCC. Also make sure you have sufficient decoupling caps.

Programming an (E)EPROM takes a high voltage, the 28C chips generate this internally. So yeah, that part could have ...

Did you confirm the /CE, /OE, and /WE signals are working?

Ah, that should probably be fixed, although I suppose the verify will fail at some point. If you feel up to fixing that, feel free by all means.

Glad you got your hardware sorted.

That's strange. I didn't specifically change the address byte order; I am using the hardware from UnaClocker which I assume is from that schematic you linked. Maybe it's a bug in the original version?

Oh, also I noticed I did implement a timeout for byte writes in the Arduino. Was the Java freezing ...

I sold out, all 10 of the boards I had made. I created a new board with rpress's revisions and just sent that off to the fab. I'll have to order some more eeproms to confirm the new design works. And rpress, I'll send you one of the new boards when they get here. :)

That would be great, thanks! I ...

Nice project. I like the use of the counter, makes it fast to go to the next address!

What are the reasons for the "sequence" in the java GUI? I see the point, if you want to verify the image that is burned, but why should I erase, clear and write in one sequence? Are there special requirements for other (E)EPROMS then 28Cxx?
Yes, most Flash memory devices require a specific erase ...

I've built the boost circuit and it works fine, I tweaked a few things to optimize it. It's nice that the voltage can be changed depending on the chip used. The Arduino sketch is unchanged, the voltage was very close to the calculation.

Another thing to consider is going with the 74HC164 instead ...

Oh somehow that's not the newest version. I played around with the buttons and briefly lost the code for that one. Anyway I updated that post with a version that should work, the same as the code in my repo. Thanks for testing it.

Ok, gave it a whirl with a 32k image on 28C256 chip, write in 4.6 seconds and verified correct. WAY faster than before, good job! I think it was taking 3-4 minutes on the old version.

Great! Also I implemented the special erase procedure from the application note, although it sounds like the ...

I have added more comments, let me know what you think.

If someone could test the 28C with page write, that would be great!
Attached is a compiled JBurn with my changes. The Arduino sketch is here. https://raw.github.com/presslab-us/MEEP ... rmware.ino

Got the Leonardo working, only mixed up one bit shift. ;D I pushed the fix to my repo. It's about 10% slower than the UNO. It's not the comms though, it's the bit swapping needed for the weird port setup. Anyway, it's plenty fast.

I ordered the parts to test the boost converter circuit. The PWM ...

Yeah I read it was faster, but I also read it takes more CPU. So I guess it depends if the higher available throughput can overcome the slower bit banging because of less available CPU. The weird port pins will probably have a speed hit too.

I pushed my changes to my repo here: https://github.com ...

Thanks Mario! I've made a bunch of changes, I'll push them to my github tomorrow so you can check it out and pull it. I've done some optimization, so now it will read 64k in 3 seconds and write in 6.5 seconds. This is much faster than my old TOP2049.

I wonder if the Leonardo might be slower because ...

Ok! I have modified UnaClocker's schematic with the transistors for VPP and A9. I also added a simple boost supply; this is not what I used as you can see in my photo, but I think it will work. Next time I order from Digikey I'll get these components to prototype it. The windowed EPROMs seem to also ...