Relatively Universal ROM Programmer – Project Update!

I’m so thrilled about the progress we’ve made on the Relatively Universal ROM Programmer! This tool has become indispensable for so many, and I couldn’t have done it without all of you. From retro computing enthusiasts to synth tinkerers and breadboard experimenters, your enthusiasm and feedback have been incredible. Hearing how this project is being used worldwide is what makes working on it so rewarding.

Updates and Improvements

Revision 2: Immediate Sell-Out and Feedback!

Revision 2 of the programmer sold out almost immediately, thanks to the overwhelming interest. Alongside the new demand came fantastic feedback, with some ideas already making their way into the latest updates.

Fixing the Feedback Loop and Voltage Control

Special thanks to Kuba0040, who highlighted a potential issue with the feedback loop potentiometer on Revision 2. If the potentiometer is overturned, the wiper might lift, potentially causing a runaway condition in the regulator. While rare, this issue has been fixed by connecting the bottom of the pot to the wiper, making the design more robust.

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On top of that, the feedback loop discussion opened up new possibilities for better control of the output voltage. While off-the-shelf DACs like I2C or SPI exist, they can cost more than the entire board—less than ideal for an affordable, open-source project. Instead, we’re exploring using an 8-bit DAC built with parallel registers, just like the ones already on the programmer. This approach is cost-effective and opens the door for digitally controlling the programming voltage.

For now, Revision 2.1 includes some solder jumper pads on the back of the board, allowing for easier adjustment of the voltage regulator feedback loop. Whether you need a higher default voltage (up to 25V for TMS2532-style ROMs) or want to experiment with digital control, the pads make it straightforward.

Fused Regulator

Revision 2.1 also includes a polyfuse on the programming voltage regulator input. The fuse, rated for 200mA, provides enough power for programming old ROMs while protecting the regulator and the ROM in the socket from accidental shorts. While it’s not foolproof (e.g., a reverse-inserted ROM might still cause damage), it’s a step in the right direction to keep the magic smoke inside.

Firestarter Firmware Updates

A big shoutout to Henrik Olsson, whose work on the Firestarter firmware and app has expanded compatibility to even more ROM types. With the latest updates, Firestarter now supports Flash-based ROMs like the SST39SF series, including the 4Mbit SST39SF040s, with software write protection built-in. Amazing work, Henrik!

What’s Next?

Digital voltage control is on the horizon, but it’s a few prototypes away from perfection. For now, Revision 2.1 is your go-to if you need a reliable programmer for old ROMs. The improvements make it more robust and user-friendly, even if we’re not yet fully digital.

Why Choose the Relatively Universal ROM Programmer?

Sure, commercial programmers like the TL866-II or T48 might be faster for certain tasks, but this project is about openness, repairability, and community. If something breaks, you can fix it. Plus, the ongoing community support makes this much more than just a tool—it’s a platform for experimentation and learning.

Rev 2.1 is for sale over @ iMania.dk for less than $9.