SONIX SN8P2624 - 2.1.4.8 Y, Z Registers

SN8P2624
8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD Page 31 Version 0.3
2.1.4.8 Y, Z REGISTERS
The Y and Z registers are the 8-bit buffers. There are three major functions of these registers.
z can be used as general working registers
z can be used as RAM data pointers with @YZ register
z 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 - - - - - - - -
¾ 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
¾ 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
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