Super Game Boy Gets Overclocked To 5.35MHz For A Retro Gaming Speed Boost

A video gaming enthusiast has overclocked a Super Game Boy. In case you are not familiar with this device, a Super Game Boy (SGB) is a Game Boy (GB) in a cartridge format. It fits into a Super Nintendo (SNES) and allows gamers to enjoy Game Boy games on the big screen. The ancient gaming device features a custom processor manufactured by Sharp which ordinarily runs at 4.295MHz, however some games ROM hacking boosted the CPU clock to 5.35MHz.

The above might be lowly MHz numbers in a world where common-or-garden variety CPUs can easily exceed these numbers but in the GHz domain. The scale of the overclock is modestly impressive, though, approaching 25%. Also, please note the Sharp chip was tweaked only in software with none of the tricks we are used to in 2023 such as extreme cooling, modifying voltages, and so on. The CPU in the SGB is actually passively cooled, with little concern for airflow.

The Super Game Boy has to feature almost a whole set of Game Boy components, as the SNES has very little in common with its portable sibling. That means the cartridge contains the same Sharp LR35902 processor, featuring both an Intel 8080 and Zilog Z80 CPU.

There is a slight discrepancy between the Super Game Boy and its portable Game Boy counterpart. The former's CPU runs at 4.295 MHz by default, and the latter at 4.19MHz. The difference was deliberate to make the cartridge-hosted GB work better with the SNES system clocks via a bridge chip dubbed the ICD2. Therefore, the SGB runs about 2.5% faster than a GB. This was noticeable to some seasoned gamers with faster on-screen action, and higher pitched / faster audio. Sadly, it also made the SGB impossible to link-cable to standard Game Boy hardware as it caused desynchronization issues - something which was fixed by the Japan-only SGB2.

So, if the meager 2.5% overclock broke some stuff, what does a 25% uplift mean to the Sharp LR35902 and the SGB system? In brief, different games react differently, but Nicole Express says that while some games benefitted from a shot of speed, there are graphics glitches to endure. The cause is likely to be the aforementioned ICD2 bridging chip and GB firmware on the SNES side not being able to keep up with an over-spec CPU on the cart. As the overclocking software switches are only accessible from the SNES side of the hardware partnership, it looks like these glitches will persist.