SN8P2740 Series
ADC, OP-amp, Comparator 8-Bit Micro-Controller
2.2.6 Y, Z REGISTERS
The Y and Z registers are the 8-bit buffers. There are three major functions of these registers.
Can be used as general working registers
Can be used as RAM data pointers with @YZ register
Can be used as ROM data pointer with the MOVC instruction for look-up table
084H
Y
Read/Write
After reset
Bit 7
YBIT7
R/W
-
Bit 6
YBIT6
R/W
-
Bit 5
YBIT5
R/W
-
Bit 4
YBIT4
R/W
-
Bit 3
YBIT3
R/W
-
Bit 2
YBIT2
R/W
-
Bit 1
YBIT1
R/W
-
Bit 0
YBIT0
R/W
-
083H
Z
Read/Write
After reset
Bit 7
ZBIT7
R/W
-
Bit 6
ZBIT6
R/W
-
Bit 5
ZBIT5
R/W
-
Bit 4
ZBIT4
R/W
-
Bit 3
ZBIT3
R/W
-
Bit 2
ZBIT2
R/W
-
Bit 1
ZBIT1
R/W
-
Bit 0
ZBIT0
R/W
-
Example: Uses Y, Z register as the data pointer to access data in the RAM address 025H of bank0.
B0MOV
B0MOV
B0MOV
Y, #00H
Z, #25H
A, @YZ
; To set RAM bank 0 for Y register
; To set location 25H for Z register
; To read a data into ACC
Example: Uses the Y, Z register as data pointer to clear the RAM data.
B0MOV
B0MOV
Y, #0
Z, #07FH
; Y = 0, bank 0
; Z = 7FH, the last address of the data memory area
CLR_YZ_BUF:
CLR
@YZ
; Clear @YZ to be zero
DECMS
JMP
Z
; Z – 1, if Z= 0, finish the routine
; Not zero
CLR_YZ_BUF
CLR
@YZ
END_CLR:
; End of clear general purpose data memory area of bank 0
…
2.2.7 R REGISTER
R register is an 8-bit buffer. There are two major functions of the register.
Can be used as working register
For store high-byte data of look-up table
(MOVC instruction executed, the high-byte data of specified ROM address will be stored in R register and the
low-byte data will be stored in ACC).
082H
R
Read/Write
After reset
Bit 7
RBIT7
R/W
-
Bit 6
RBIT6
R/W
-
Bit 5
RBIT5
R/W
-
Bit 4
RBIT4
R/W
-
Bit 3
RBIT3
R/W
-
Bit 2
RBIT2
R/W
-
Bit 1
RBIT1
R/W
-
Bit 0
RBIT0
R/W
-
Note: Please refer to the “LOOK-UP TABLE DESCRIPTION” about R register look-up table application.
SONiX TECHNOLOGY CO., LTD
Page 30
Version 2.0
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