* This specification are subject to be changed without notice.

EM83049

KEYBOARD ENCODER

4

5.2.1997

- Responds ACK.

- Updates status indicators.

- Returns to previous scanning state.

Echo ( Hex EEH )

- Responds with EE hex.

- Returns to previous scanning state.

Invalid commands ( Hex EF and F1 )

- Returns a RESEND command.

- Returns to previous scanning state.

Select Alternate Scan Codes ( Hex F0 )

- Responds ACK.

- Clears output buffer.

- Sets the default typematic rate/delay.

- Clears last typematic key.

- Receives option byte.

- Responds ACK.

- Option byte =

01 : selects scan code set 1

02 : selects scan code set 2

03 : selects scan code set 3

- Returns to previous scanning rate.

Read ID (F2)

- Responds with ACK.

- Discontinues scanning.

- Sends two ID bytes. The second byte will be sent within 500 uS after first byte.

- Resumes scanning.

Set Typematic Rate/Delay ( Hex F3 )

- Responds ACK.

- Receives rate/delay value byte

- Responds ACK.

- Set rate/delay (* Note 1)

- Returns to previous scanning state.

* Note 1

1. Repeat period = ( 8+A ) x ( 2B) x 0.00417 seconds

A : binary value of bits 2, 1, and 0.

B : binary value of bits 4 and 3.

2. Delay = ( C +1 ) x 250 milliseconds

C : binary value of bits 6 and 5. Bit 7 is always 0.