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USB keyboards can get around the ten key limitation by presenting themselves as multiple devices.
by Freaky 11y ago
USB keyboards can get around the ten key limitation by presenting themselves as multiple devices.
- 0xD000000D 11y agoOr by using a passive USB to PS/2 adapter. USB and PS/2 are both serial protocols with similar wiring, so a USB keyboard that supports passive adapters can detect what kind of port it is plugged into when powered on, then send unmodified PS/2 through the USB cable. For this reason, there are a few mechanical keyboards that only support N-key rollover in PS/2 mode, dropping down to 10-key rollover in USB-HID mode (it's cheaper and less likely to cause bugs than presenting as multiple HIDs, and anyone that cares about N-key rollover probably has a PS/2 port anyway).