SNES EPROM Programmer with Arduino

Most video game manufacturers aren’t too keen on homebrew games, or people trying to get more utility out of a video game system than it was designed to have. While some effort is made to keep people from slapping a modchip on an Xbox or from running an emulator for a Playstation, it’s almost completely impossible to stop some of the hardware hacking that is common on older cartridge-based games. The only limit is usually the cost of an EPROM programmer, but [Robson] has that covered now with his Arduino-based SNES EPROM programmer.

Normally this type of hack involves finding any cartridge for the SNES at the lowest possible value, burning an EPROM with the game that you really want, and then swapping the new programmed memory with the one in the worthless cartridge. Even though most programmers are pricey, it’s actually not that difficult to write bits to this type of memory. [Robson] runs us through all of the steps to get an Arduino set up to program these types of memory, and then puts it all together into a Super Nintendo where it looks exactly like the real thing.

If you don’t have an SNES lying around, it’s possible to perform a similar end-around on a Sega Genesis as well. And, if you’re more youthful than those of us that grew up in the 16-bit era, there’s a pretty decent homebrew community that has sprung up around the Nintendo DS and 3DS, too.

Thanks to [Rafael] for the tip!

Staring at the Sun: Erasing an EPROM

Flash memory is the king today. Our microcontrollers have it embedded on the die. Phones, tablets, and computers run from flash. If you need re-writable long term storage, flash is the way to go. It hasn’t always been this way though. Only a few years ago EPROM was the only show in town. EPROM typically is burned out-of-circuit in a programming fixture. When the time comes to erase the EPROM, just pop it under an ultraviolet (UV) bulb for 30 minutes, and you’re ready to go again. The EPROM’s quartz window allows UV light to strike the silicon die, erasing the memory.

The problem arises when you want to use an EPROM for long term storage. EPROM erasers weren’t the only way to blank a chip. The sun will do it in a matter of weeks. Even flourescent light will do it — though it could take years.

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Voja’s EEPROM Emulator From 1991

We’re glad we’re not the only hacker-packrats out there! [Voja Antonic] recently stumbled on an EPROM emulator that he’d made way back in 1991. It’s a sweet build, so take your mind back 25 years if you can. Put on “Nevermind” and dig into a nicely done retro project.

The emulator is basically a PIC 16C54 microcontroller and some memory, with some buffers for input and output. On one side, it’s a plug-in replacement for an EPROM — the flash memory of a bygone era. On the other side, it connects via serial port to a PC. Instead of going through the tedious process of pulling the EPROM, erasing and reprogramming it, this device uploads new code in a jiffy.


No need to emulate ancient EPROMS? You should still check out this build — the mechanics are great! We love the serial-port backplane that is soldered on at a 90° angle. The joint is a card-edge connector electrically, but also into a nice little box, reminiscent of [Voja]’s other FR4 fabrication tricks. The drilled hole with the LED poking out is classy. We’re never going to make an EPROM emulator, but we’re absolutely going to steal some of the fabrication techniques.

[Voja] is a Hackaday contributor, badge-designer, mad hacker, inspired clock-builder, and developer of (then) Yugoslavia’s first DIY PC.


[glitch] had a cheap EPROM eraser with very few features. Actually, that might be giving it too much credit: it’s barely more than a UV light that turns on when it’s plugged in and turns off when it’s plugged out unplugged. Of course it would be nice to implement some safety features, so he decided he’d hook it up to a software-controlled power outlet.

Of course, controlling a relay that’s wired to mains is old hat around here, and in fact, we’ve covered [glitch]’s optoisolated mains switch already. He’s gone a little beyond the normal mains relay project with this one, though. Rather than use a microcontroller to run the relay, [glitch] wrote a simple Ruby script on his computer to turn the EPROM eraser on for the precise amount of time that is required to erase the memory.The Ruby script drives the relay control directly over a USB to serial adapter’s RTS handshake pin.

[glitch]’s hack reminds us that if you just need a quick couple bits of slow output, a USB-serial converter might be just the ticket. You could imagine driving everything from standard lamps to your 3D printer’s bed heater (provided you use similar hardware), but it’s especially helpful for [glitch] who claims to forget to turn off the eraser when it’s done its job, which leaves a potentially dangerous UV source just lying about. It’s always a good idea to add safety features to a dangerous piece of equipment!

Mostly Non-Volatile Memory With Supercapacitors

Back in the days of old, computers used EPROMs to store their most vital data – usually character maps and a BASIC interpreter. The nature of these EPROMs meant you could write to them easily enough, but erasing them meant putting them under an ultraviolet light. Times have changed and now we have EEPROMs, which can be erased electronically, and Flash, the latest and greatest technology that would by any other name be called an EEPROM. [Nicholas] wanted an alternative to these 27xx-series EPROMs, and found his answer in supercapacitors.

[Nick]’s creation is a mostly non-volatile memory built around an old 62256 32k SRAM. SRAM is completely unlike EPROMs or Flash, in that it requires power to keep all its bits in memory. Capacitor technology has improved dramatically since the 1980s, and by using a supercap and one of these RAM chips, [Nick] has created a substitute for a 27-series EPROM that keeps all its memory alive for days at a time.

The circuit requires a small bit of electronics tucked between the EPROM socket and the SRAM chip; just enough to turn the 12 Volts coming from the EPROM programming pin to the 5 Volts expected from the SRAM’s Write Enable pin. This is accomplished by a few LEDs in series, and a 0.1F 5.5V supercap which keeps the SRAM alive when the power is off.

As for why anyone would want to do this when modern technologies like Flash can be found, we can think of two reasons. For strange EPROM sizes, old SRAMs abound, but a suitable Flash chip in the right package (and the right voltage) might be very hard to find. Also, EEPROMs have a write lifetime; SRAMs can be written to an infinite number of times. It’s not the best solution in every case, but it is certainly interesting, and could be useful for more than a few vintage computing enthusiasts.

This project makes us think of another where an LED may have been supplying keep-alive power to some volatile memory.

Dumping Old PROMs With New Hardware

[ijsf] recently came across a very old synthesizer from a defunct West German company. This was one of the first wavetable synths available, and it’s exceptionally rare. Being so rare, there isn’t much documentation on the machine. In an attempt at reverse engineering, [ijsf] decided to dump the EPROMs and take a peek at what made this synth work. There wasn’t an EPROM programmer around to dump the data, but [ijsf] did have a few ARM boards around. It turns out building a 27-series PROM dumper is pretty easy, giving [ijsf] an easy way to dig into the code on this machine.

The old EPROMs in this machine have 5v logic, so [ijsf] needed to find a board that had a ton of IOs and 5v tolerant inputs. He found the LPC2148, which has a nice USB system that can be programmed to dump the contents of a PROM over serial. Interfacing the PROM is as simple as connecting the power and ground, the address lines, data, and the signal lines. After that, it’s just a matter of stepping through every address according to the timing requirements of the PROM. All the data was dumped over a serial interface, and in just a few seconds, [ijsf] had 32768 bytes of ancient data that made this old synth tick.

EPROM Coffee Table

Either in need of a coffee table or suffering a severe lack of upscaled electronics, [Darren] just finished up a great build for his living room. It’s a huge, scaled up version of a UV erasable EPROM with an infinity mirror in place of the fused quartz window.

[Darren]’s coffee table was inspired by an earlier build by the geniuses at Evil Mad Scientist. A few years ago, they built a 555 footstool that was scaled up about 30 times its normal size. Even at footstool scale, the 555 is still relatively tiny.

[Darren] is using a similar construction technique by forming the legs of the EPROM out of laminated plywood. Since this build is significantly larger, building the entire device out of solid, laminated plywood would result in an unwieldy and expensive piece of furniture. Instead, [Darren] constructed the legs and sides out of plywood laminations, covering the ends, top, and bottom with plywood panels. The result is a hollow EPROM/coffee table that’s still structurally sound.

If you’re a bit confused after counting the number of pins on the coffee table, you’re in good company. This is technically a scaled-up version of a 16-pin 0.600″ PDIP, something that a quick googling suggest isn’t historically accurate. Maybe there was an EPROM with a 4-bit wide data bus somewhere in the annals of electronics history, but we’re happy with saying that a completely accurate scaled-up ROM would be far too big for [Darren]’s living room.

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