User's Manual

3.5.3 Keyboard monitors the clock line(10 ㎳ intervals)and detects the active level.

3.5.4 Keyboard detects -RTS-on the data line and clocks it in as the logic 0 start

bit. then clocks 8 data bits and parity.

3.5.5 Keyboard looks for a logic 1 on the data line then forces it low clocks one

more bit. This action signals the system that the keyboard has received the

data. If the data line is not at logic level 0 following the 10th bit, the

keyboard will continue to clock bits until the line becomes active. The

keyboard then pulls data line low and transmits a resends.

4.0 FIFO

4.1 FIFO Capacity

4.1.1. The keyboard contains at least a 16-byte first-in-first-out(FIFO)buffer. The

keyboard stores the scan codes until the system is ready to receive them.

4.2 Overrun Conditions

4.2.1 A buffer-overrun condition occurs when the keyboard tries to place more

characters than the keyboard buffer can hold. When this occurs, an overrun

code(FFH for scan code set 1, and 00H for scan code sets 2&3)replaces the

last byte. If more keys are pressed before the system allows keyboard

output, the additional data lost.

4.3 Special Cases

4.3.1 When the keyboard is allowed send data, the bytes in the buffer will be sent

as in normal operation, and new data entered is detected and sent. Response

codes do not occupy a buffer position.

4.3.2 If keystrokes generate a multiple-byte sequence, the entire sequence must fit

into the available buffer space or the keystroke is discarded and a buffer

overrun condition occurs.

5.0 KETS

5.1 Key Type Description

5.1.1 While using scan code sets 1&2, all the keys on the keyboard are

make/break (M/B) except station 16. Scan code set 3 default conditions are

given in the code tables. The make scan code is sent to the system when

the key is depressed and the break code is sent when the key is released.

5.2 Auto-Repeat Protocol

5.2.1 If a key is typmatic (auto-repeats), the key will auto-repeat after the initial

delay has expired. Rollover to another auto-repeat key will stop repeating

operation and will produce the scan code for the second key. After an initial

delay, the keyboard will the second code.

6.0 PC CABLE CONNECTOR

6.1 Pinout Table

6pin

5pin

DIN

Signal Type

5 1 KBD Clk I/O

1 2 KBD data I/O

2 3

3 4 Ground Power

4 5 +5.0Vdc Power