Microsoft mouse. Serial 1200 bps, 7N1, 3 byte packets (sync + buttons + high bits X and Y, low bits X, low bits Y. Mouse Systems mouse. Serial 1200 bps, 8N1, 5 byte packets (sync + buttons, X, Y, delta X since X, delta Y since Y).

PS/2 mouse. Serial 10000-16667 bps, 8O1, 3 byte packets (sync + buttons + direction + overflow, delta X, delta Y). Mouse can receive commands, 0FFh reset, recognizes 3 modes of operation (stream - sends data when mouse moves, remote - sends data when polled, wrap - echoes received data).