Some time ago, I mentioned that I had been unable to test the various ROMs in the UK101, lacking an EPROM programmer. That has now been rectified, thanks to the fine work of Tom Nisbet, creator of TommyPROM.
In addition to an Arduino sketch, the Github linked above hosts a couple of circuit boards, and I had them made as part of my last order from Seeed Studio.
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| TommyPROM with a very old 2716 EPROM |
Populating this PCB cost under €10, quite the bargain. This version of the programmer can read 27-series EPROMs but can't manage the voltages required to program them.
Configuring the programmer requires editing the Arduino sketch for chip series and type, and uploading the modified sketch. This wouldn't pass muster in a commercial product but is absolutely fine for this project's target market: hobbyists on a budget.
Opening a serial port to the board shows the following menu:
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| Main Menu |
Reading that EPROM, which is nearly 40 years old, produced the following output:
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| Amnesia? |
Unsurprisingly, given its age, it seems to have lost its memory! Luckily it is not too difficult to find copies of UK101 (and Superboard) firmware online, Mark's Lab has copies for instance.
Burning old-school 27-series EPROMs requires more advanced hardware, and the second TommyPROM board I had made can do it, TommyPROM32. I will review that iteration when I have assembled it.
What the current version of TommyPROM can do is write to 28-series EEPROMs, e.g., an AT28C16. This is pin-compatible with the 2716 so once it arrives and has been programmed, the next step in testing the UK101 can be taken: hooking the board up to a logic analyser and spying on the data bus using another fine Open Source tool: 6502Decoder.
(I have several PCBs left over from that order. If you want one at cost, PM me.)
Update (April 2024): after some further investigation, it turns out that the basic TommyPROM can only handle 28-pin chips so any data retrieved from smaller chips (as above) won't be valid. TommyPROM32 is definitely the way to go here. Stay tuned for a review of that coming soon!
