The PlayStation one console. (Image Credit: Vance A./Unsplash)
This caught my eye recently looking at ways people have modified old consoles. It's quite an achievement, despite the end results.
Over 30 years ago, the PlayStation one console officially launched with 2MB RAM. Recently, with the help of the PSX dev Discord community, TunerTom expanded its memory capacity from 2MB to 16MB. With this upgrade, the console’s capabilities can expand through custom software and hardware projects.
Many PlayStation fanatics believed the console had an 8MB memory limit, as the ISA and PCI development cards shipped with that amount of RAM. This inspired earlier memory expansion projects. Later on, modder TunerTom spoke to developer Spicy JPEG and researched PlayStation arcade boards. He discovered some of these boards feature 16 MB RAM. By analyzing the wiring configuration, he noticed the CPU can handle up to 16 MB, and Sony never enabled that on its systems.
TunerTom installed eight times more RAM to the PS one console. (Image Credit: Macho Nacho Productions/YouTube)
The modder removed the four 512KB EDO DRAM chips in the PS One, replacing them with eight 2MB chips taken from legacy EDO memory modules. Since the motherboard has space for four chips, he installed those before stacking the other four on top. Several motherboard signals were then rerouted using a custom quick solder board.
After he installed the RAM chips, a diagnostic program verified that the console recognized and accessed the 16MB RAM. This matches the configuration in some PlayStation arcade hardware. It only works on PU-8 motherboards, similar to those in SCPH-5500 consoles.
Wiring to route the signals. (Image Credit: Macho Nacho Productions/YouTube)
However, adding more RAM to the PS One doesn’t mean existing games will run better. Games were developed around the console’s 2MB RAM, which means they won’t notice any additional RAM. You can expect normal performance. Even then, the mod isn’t universally compatible. Certain games access system memory in unusual ways, leading to crashes or bootup issues. For instance, Final Fantasy IX wouldn’t move past the PS startup screen.
Installing RAM gives developers greater flexibility by reducing the amount of data that must be frequently loaded and unloaded. More detailed assets can then remain stored in memory. This is shown in a modified Gran Turismo 2 game. It loads higher-detail vehicle models throughout races rather than switching to simpler models to save memory.
With the upgrade, homebrew ports could be simplified. The Super Mario 64 PlayStation port developer says 16 MB of memory reduces complex memory management during development. And more game data can be loaded at once instead of streaming assets.
TunerTom continues to improve the system. He’s working on upgrading the video memory from 1MB to 2MB. Additionally, he plans to expand the console’s sound RAM to make it closely resemble the hardware used in the arcade systems.
It’s still a challenging build due to sourcing compatible memory chips. This modification requires older EDO RAM modules that aren’t very easy to find. To solve that problem, the modder is identifying modern replacement chips to make the upgrade accessible for future builders.
On a related note, the Sega Saturn has a 4MB expansion cartridge you could get that would open up new features the PlayStation didn't have. So, maybe, the PSX upgrade might unlock crossplatform game features? Time will tell.
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