The PS1 BIOS Supports the Mouse

Post by **MasterLink** » March 27th, 2025, 11:01 am

Perhaps not news to many, but this was something I wondered for 30 years, if the PS1 BIOS even supported the mouse at all since the cursor resembled a mouse cursor. After finally obtaining a PS1 mouse, it DOES support the mouse! But not only that, the cursor changes into a crosshair.

Screenshot 2025-03-26 195746.png

I somehow both expected the mouse to work, and possibly not, but I most certainly didn't expect that the cursor also changes its shape as well.

I tried in emulators to no avail, but when I got the PS1 mouse, I learned it is supposed to be in port 1 per the box, whereas when I tried this on emulators I only ever put the mouse virtually on port 2, not knowing it wasn't supposed to be in that port for the BIOS interface.

Post by **MottZilla** » Yesterday, 7:21 pm

That is actually very interesting. I never would have thought that would be a thing.

I always thought it was a bummer that WarCraft II on Playstation doesn't actually support the mouse. It seems a fair number of titles do support it. And it seems there are some projects to make USB Mice/Keyboard to PS1 adapters. I may have to keep in mind that the Mouse exists for homebrew projects.

Post by **roseblack** » Yesterday, 8:32 pm

It's really cool to know that the PS1 BIOS not only supports the mouse but also changes the cursor to a crosshair, this opens up a lot of new potential for homebrew projects and improves the user experience on the classic console!

Post by **Administrator** » Yesterday, 8:45 pm

It has been known for a long time that the BIOS supported the mouse. It's just that a lot of PlayStation 1 gamers didn't use the mouse so it was a hidden feature. It's somewhat like the file allocation table undelete command for Memory Cards in the BIOS, albeit that one is truly hidden but if I recall it was documented in a game manual which is how it was found (and it was also found by reverse engineering the BIOS).