SN8P1602B
8-Bit Micro-Controller
WORKING REGISTERS
These Y,Z registers can be used as the general-purpose working buffer or access ROM’s and RAM’s data. For
instance, all of the ROM table can be looked-up by Y and Z registers. The data of RAM memory can be indirectly
accessed with Y and Z registers.
Y, Z REGISTERS
The Y and Z registers are the 8-bit buffers. There are three major functions of these registers.
ꢄ
ꢄ
ꢄ
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
0
Bit 6
YBIT6
R/W
0
Bit 5
YBIT5
R/W
0
Bit 4
YBIT4
R/W
0
Bit 3
YBIT3
R/W
0
Bit 2
YBIT2
R/W
0
Bit 1
YBIT1
R/W
0
Bit 0
YBIT0
R/W
0
083H
Z
Read/Write
After reset
Bit 7
ZBIT7
R/W
0
Bit 6
ZBIT6
R/W
0
Bit 5
ZBIT5
R/W
0
Bit 4
ZBIT4
R/W
0
Bit 3
ZBIT3
R/W
0
Bit 2
ZBIT2
R/W
0
Bit 1
ZBIT1
R/W
0
Bit 0
ZBIT0
R/W
0
ꢁ
Example: uses YZ 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 YZ register as data pointer to clear the RAM data
B0MOV
B0MOV
Y, #0
Z, #07FH
; Y = 0, bank 0
; Y = 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
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Version 1.1
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