SONIX SN8P2501D - Y, Z Registers; R Register

SN8P2501D
8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD Page 26 Version 1.5
2.2.5 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
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Y
YBIT7
YBIT6
YBIT5
YBIT4
YBIT3
YBIT2
YBIT1
YBIT0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
After reset
-
-
-
-
-
-
-
-
083H
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Z
ZBIT7
ZBIT6
ZBIT5
ZBIT4
ZBIT3
ZBIT2
ZBIT1
ZBIT0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
After reset
-
-
-
-
-
-
-
-
 Example: Uses Y, Z register as the data pointer to access data in the RAM address 025H of bank0.
B0MOV
Y, #00H
; To set RAM bank 0 for Y register
B0MOV
Z, #25H
; To set location 25H for Z register
B0MOV
A, @YZ
; To read a data into ACC
 Example: Uses the Y, Z register as data pointer to clear the RAM data.
B0MOV
Y, #0
; Y = 0, bank 0
B0MOV
Z, #07FH
; Z = 7FH, the last address of the data memory area
CLR_YZ_BUF:
CLR
@YZ
; Clear @YZ to be zero
DECMS
Z
; Z – 1, if Z= 0, finish the routine
JMP
CLR_YZ_BUF
; Not zero
CLR
@YZ
END_CLR:
; End of clear general purpose data memory area of bank 0
…
2.2.6 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
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R
RBIT7
RBIT6
RBIT5
RBIT4
RBIT3
RBIT2
RBIT1
RBIT0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
After reset
-
-
-
-
-
-
-
-
 Note: Please refer to the “LOOK-UP TABLE DESCRIPTION” about R register look-up table application.