Tandy 1400LT Service Manual page 278

REAL TIME CLOCK
Address allocation of MODE 00 (Note 1)
Address
I
MODE
I
MODE 00
070H
071H
072H
I
A3
-
A1
I
Contents
I
D3
I
D2
I
D1
I
DO
0
1-sec counter
1 10-sec counter X
2 1-min counter
074H
075H
076H
073H
I
3
I
lo-min counter
1 x 1 1 1
4 1-hour counter
5 10-hour counter (Note
2)
X X
6 Day-of-the-weed counter
X
078H
077H
I
7
I
1-day counter
I
1 1 1
8
10-day counter X X
079H
07AH
I
A
I
10-month counter I X I X I X I
9
I
1-month counter
07BH
I
B
I
1-year counter
I 1 1 1
07CH
07DH
~
C 10-year counter
D MODE Register
Timer Alarm
I
EN
MODE selector
M1 M2
X indicates that the counter may take any value during write operation, but always be 0 when read out.
(Note 1) MODE 00 is set by writing data ( X, X, 0, 0) to address 07DH.
(Note 2) Bit 1 of the 10-hour counter should be as follows when the 12-hour system is selected:
D1
=
1 (PM)
D1
=
0 (AM)
Address allocation of MODE 01 (Note 1)
Address
1
MODE
1
MODE 01
07EH
07FH
1
A3
-
A1
I
Contents
I
D3
I
D2
I
D1
I
DO
E Test Register Test 3 Test 2 Test 1 Test 0
Timer Alarm
16Hz ON RESET RESET
F RESET Controller 1Hz ON
070H
072H
I
2
I
Alarm 1-min register
I 1 1 1
0
X X X X
073H
I
3
I
Alarm 10-min register
1 x 1 1 1
071H 1 X
x
X
X
076H
I
6
I
Alarm day-of-the-week register
I
X
I 1 1
074H 4
075H 5
Alarm -chow register
Alarm 10-hour register X X
07DH
I
D
1
MODE Register
~~~
077H
078H
079H
07AH
07BH
07CH
~
7 Alarm 1-day register
8
Alarm 10-day register X X
9 X X X X
A 12-hour/24-hour selector X X X
B Leap-year counter X X
C X X X X
Timer Alarm
~
_ _ _ _ _ _ _ _
(Note 1) MODE 01 is set by writing data (X,
X,
0, 1) to address 07DH.
MODE selector
M1 MO
F-9
07EH
07FH
E Test Register Test 3 Test 2 Test 1 Test 0
1 Hz 1 a z Timer Alarm
ON ON RESET RESET
F RESET Controller
__
-
-