SN8P2740 Series
ADC, OP-amp, Comparator 8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 29
Version 2.0
2.2.5 H, L REGISTERS
The H and L registers are the 8-bit buffers. There are two major functions of these registers.
Can be used as general working registers
Can be used as RAM data pointers with @HL register
081H
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
H
HBIT7
HBIT6
HBIT5
HBIT4
HBIT3
HBIT2
HBIT1
HBIT0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
After reset
-
-
-
-
-
-
-
-
080H
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
L
LBIT7
LBIT6
LBIT5
LBIT4
LBIT3
LBIT2
LBIT1
LBIT0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
After reset
-
-
-
-
-
-
-
-
Example: If want to read a data from RAM address 20H of bank_0, it can use indirectly addressing mode
to access data as following.
B0MOV
H, #00H
; To set RAM bank 0 for H register
B0MOV
L, #20H
; To set location 20H for L register
B0MOV
A, @HL
; To read a data into ACC
Example: Clear general-purpose data memory area of bank 0 using @HL register.
CLR
H
; H = 0, bank 0
B0MOV
L, #07FH
; L = 7FH, the last address of the data memory area
CLR_HL_BUF:
CLR
@HL
; Clear @HL to be zero
DECMS
L
; L
– 1, if L = 0, finish the routine
JMP
CLR_HL_BUF
; Not zero
CLR
@HL
END_CLR:
; End of clear general purpose data memory area of bank 0
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