Keyboard Technical Information [PC98]

Type	Separated
LSI	Main board: uPD8251A Keyboard: uPD8048
Data Lines	6 lines: GND, +5V, Data lines, 3 Control lines
Data Transfer	Asynchronous serial communication Speed: 19,2Kbps Length: 8 bits Start bit: 1 Stop bit: 1 Parity bit; Odd Level: TTL
Data Causing	Key-down causes Make data. Key-up causes Break data. Pressing a key over 0.5 seconds, keyboard repeats Break/Make data. The order of key data is not specified.

I/O address

Descriptions

00xx0100A₀1

Keyboard Interface uPD8251A

A₀	Input operation (Read)
0	8251A Data Read
1	8251A Status Read

Data Read Format

D₇	D₆	D₅	D₄	D₃	D₂	D₁	D₀
Break/!Make	Key Code

Status Read Format

A₀	Output operation (Write)
0	8251A Data Write
1	8251A Mode/Command Write

Mode Instruction Format

D₇	D₆	D₅	D₄	D₃	D₂	D₁	D₀
0	1	0	1	1	1	1	0

Command Instruction Format