Ac C E Ssing The Rtc Internal Rah - Sharp MZ-5500 Tehnical Manual

13-2. Accessing the RTC internal RAM
Total 26 nibbles internal RAM are provided in the RP5C01 RTC for the Mode 10
and 11 as shown in Table 2-13-3, they are the battery backed up RAM, though
not so large in capacity . But, all RÄMs. for Mode 10 are reserved by the
~ystem and those Mode ~ 1 are user accessible.
Se~
the flowchart below for the accessing methode
[Ex.]
(1)
Write
To write the 4-bit da ta 5H in the
STAAT
addre?s OA of Mode 11.
Select RAH block
Set mode register
(0, ,
0 , ,0
, , 0
0 ) -
(X, X ,1,0)
OA (X
,x
,1,1)
SSUB:
Write data in RAM
NO
ESUB:
f N
o
(2) Read
To read
STAAT
of Mode
Select RAM block
Set mode register
, (D.,D.,D"Do)-(X,X,I,O)
OA
(X,X,I,I)
Read RAM data
E N
*Nibble
NO
CALL SSUB
MOV DX,22AH
MOV AL,05H
OUT DX,AL
CALL ESUß
HOV
IN
OR
OUT
RET
HOV
IN
AND
OUT
RET
DX,22DH
AL,DX
AL,03H
DX,AL
DX,22DH
AL,DX
AL,OCH
DX,AL
the 4-bit data in the
11 and to store it in
address
DL.
OA
CALL
HOV
IN
AND
MOV
CALL
SSUB
DX,22AH
AL,DX
AL,OFIl
DL,AL
ESUB
=
4 bits