case 0b01010000:
case 0b11010000:
// AT-done
+ // DO NOT check stop bit. Zenith Z-150(AT) asserts stop bit as low for no reason.
+ // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#zenith-z-150-beige
// TODO: parity check?
isr_state = isr_state>>6;
ibmpc_protocol = IBMPC_PROTOCOL_AT;