3-10. Status Register A; Real-Time Clock Bytes (Hex 000-000) - IBM Personal System/2 60 Technical Reference

Real-Time Clock Bytes (Hex 000-000)
Bit definitions and addresses for the real-time clock bytes are shown
in the following figure.
Address Byte
(Hex) Function Number
000 Seconds 0
001 Second Alarm 1
002 Minutes 2
003 Minute Alarm 3
004 Hours 4
005 Hour Alarm 5
006 Day of Week
6
007 Date of Month
7
008 Month 8
009 Year
9
OOA Status Register A 10
OOB Status Register B 11
ooe
Status Register
e
12
OOD Status Register D 13
Figure 3-9.
Real-Time Clock Bytes
Note: The Setup program initializes status registers A, B, C, and D
when the time and date are set. Interrupt hex 1A is the BIOS
interface to read and set the time and date and it initializes the
register the same way as the Setup program.
Status Register A (Hex OOA)
Bit Function
7 Update in Progress
6 - 4 22-Stage Divider
3 - 0 Rate Selection Bits
Figure 3-10. Status Register A
Bit 7 When set to 1, this bit indicates the time-update cycle is in
progress. When set to 0, it indicates the current date and
time can be read.
Model 60 System Board 3-13