As we all know, when developing software for any platform or simply hacking a bit of code to probe how something works, the ability to deploy code rapidly is a huge help. [Martin Donlon], aka [wickerwaka], is well known in retro gaming and arcade hardware reverse engineering circles and had the usual issues figuring out how an arcade CPU board worked while developing a MiSTer core. Some interesting ASICs needed quite a bit of poking, and changing the contents of socketed ERPOMs is a labour-intensive process. The solution was PicoROM, a nicely designed ROM emulator in a handy DIP-32 form factor.

As the title suggests, PicoROM is based on the Raspberry Pi RP2040. It emulates an 8-bit ROM up to 2MBits in size with speeds up to 100ns. Since it uses the RP2040, USB connectivity is simple, enabling rapid uploading of new images to one (or more) PicoROMs in mere seconds. A vertically orientated USB-C connector allows multiple PicoROMs to be cabled to the host without interfering with neighbouring hardware. The firmware running on core 1 passes data from the internal 264K SRAM, using the PIO block as a bus interface to the target. A neat firmware feature is the addition of a mechanism to use a ROM region as a bidirectional control channel, which the software running on the target can use to communicate back to the host computer. This allows remote triggering of actions and the reporting of responses. Responses which may not be physically observable externally. [Martin] is using this feature extensively to help probe the functionality of some special function chips on the target boards, which is still a slow process but helped massively by reducing that critical software iteration time. The PCB was designed with KiCAD. The project files for which can be found here.

This isn’t the first time we’ve seen the RP2040 used for ROM emulation; here’s a pile of wires that does the same job. It just isn’t as pretty. Of course, if you really must use EPROMs, then you could give this sweet programmer a look over.

For fans of retro games, Pac-Man is nothing short of iconic—a game so loved it’s been ported to nearly every console imaginable. But the Atari 2600 version, released in 1982, left players scratching their heads – as laid out in a video by [Almost Something]. Atari had licensed Pac-Man to ride the wave of its arcade success, but the home version, programmed solely by [Todd Fry], missed the mark, turning an arcade icon into a surprising lesson in over-ambitious marketing.

Despite the hype, [Fry] faced an almost impossible task: translating Pac-Man’s detailed graphics and complex gameplay to the Atari’s limited 4 K cartridge with only 128 bytes of RAM. Atari’s strict limitations on black backgrounds and its choice to cut costs by sticking with a 4 K cartridge left the game barely recognizable. The famous pellet-chomping maze became simpler, colors were changed, and the iconic ghosts—reduced to single colors—flickered constantly. And then, Atari went all in, producing twelve million copies, betting on the success of universal appeal. In a twist, Pac-Man did sell in record numbers (over seven million copies) but still fell short of Atari’s expectations, leaving millions of unsold cartridges eventually dumped in a New Mexico landfill.

This debacle even kind of marked Atari’s 1983 decline. Still, Pac-Man survived the hiccup, evolving and outlasting its flawed adaptation on the 2600. If you’re interested in learning more about the ins and outs of game ports, check out the fantastic talk [Bob Hickman] gave during Supercon 2023.