That is a limitation of the keyboard not PS/2. Unlike USB which is limited to 10 simultaneous key presses, PS/2 supports full n-key rollover.
USB is not limited to 10, or 6 as is sometimes stated.
This, it’s why I still use the PS2 interface. Full n-key rollover is impossible for me to do without.
Ah, had to dig into it. There was a long period of time during which you couldn’t find a USB NKRO keyboard. Seems that has been fixed.
Out of curiosity, what is the practical use of full N-key rollover? I can’t think of many things that require me to press more than maybe five keys at a time.
Used to have these problems when we were children and playing fighting games with my brother with one keyboard or guitar hero clones that need you to press multiple buttons at the same time, that’s the only use case I could think of. I don’t know if there’s any modern software that requires you to mash more than 2 or 3 buttons at the same time