Commands from the system to the keyboard:
ED Set/Reset status indicators  (CapsLock, NumLock, ScrolLock in low bits)
EE Echo
EF Invalid command
F0 Select alternate scan codes
F1 Invalid command
F2 Read ID
F3 Set typamatic rate/delay
F4 Enable
F5 Default disable
F6 Set default
F7 Set all keys - Typematic
F8              - Make/Break
F9              - Make
FA              - Typematic/Make/Break
FB Set key type - Typematic
FC              - Make/Break
FD              - Make
FE Resend
FF Reset
Commands sent from the keyboard to the host:
00 Key detection error/overrun (code sets 2 or 3)
83AB Keyboard ID
AA Basic Assurance Test (BAT) completion code
FC BAT failure code
EE Echo
FA Acknowledge (ACK)
FE Resend
FF Key detection error/overrun (code set 1)
Source: an old PS/2 tech reference manual that for some reason is
still in my bookcase...