ET-3400 ROM - Programming the EEPROM

Only a few months ago I needed a Universal programmer so I could program GALs and some newer/larger EPROMs that my old home made Electronics Australia 1993 EPROM programmer could not program. I was considering the popular TL866-II Plus that a lot of people are recommending due to the low cost. Some reviews stated that it had issues with programming certain brands of GALs so I was hesitant against purchasing one. While shopping for something more capable I was lucky enough to score this basic model Wellon VP-299 Universal Programmer on eBay for a low $50AU. Typically these are $250AU or more. Unfortunately it failed one week later after I had pushed it a bit hard with some known faulty EPROMs. Two months later I finally had it working again.


The patched OUTCH monitor routine is shown listed below the programmer and I've circled the five bytes that need to be amended. These are for the address in ROM that the 1K is mapped to. The equivalent byte in the EEPROM will be whatever 1K bank I want to put it in. As I've chosen to put the patched version of the monitor in bank 3, this means the byte at $FE3F above will be in EEPROM location $0E3F, the byte at $FE40 will be in EEPROM location $0E40 and so forth.

I already created the new ROM previously, and this is a screen shot of the software for the Wellon VP-299. It's pretty similar to other Universal programmer software so I found it very easy to use. First thing you do is Select the device you are programming. The software remembers the last device you selected whenever you run it. To check what that is you can see the lower part of the window that shows I have an ATMEL E/EPROM AT28C64 28 pin. Check. Further down you can see it is 2000H bytes long, or 8K in decimal.


After Loading the ROM data into the buffer I used the Edit button to check that the patched bytes are where I think they should be, and they are.
With an EEPROM there is no option to Erase it, and no reason to Blank Check it, unlike you would do for a UV EPROM. You simply load the ROM data into the buffer and hit the Prog button. The EEPROM is erased and programmed in one go.

The EEPROM programmed successfully so the next step is to install it and test it out in circuit...


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