Timer; I/O Address - Sanyo MBC-550 Series User Manual

Timer 8253
This
8253 has three channels for timer counters,
equipment uses three channels as the interval timer,
tone oscillator, and baud rate generator respectively.
Its allocation is as follows:
I/O Address
78.6 KHz
u
CO
OUT1
8259A IRO (10 msec in period at initialization)
20 H
Counter 0
ci
OUT1
22H 8259A IR1
Counter 1
C2
OUT2
RS-232C Baud rate (1200 bps at initializatio^^^
24H
Counter 2
8253 Control
26H
1.78977 MHz
5-36