CALL address
Machine code
Description
Operation
CLC
Machine code
Description
Operation
DAA
Machine code
Description
Operation
DEC A
Machine code
Description
Operation
DEC Rn
Machine code
Description
Operation
DEC [R1R0]
Machine code
Description
Operation
Preliminary
HTG1390
Subroutine call
1111aaaa aaaaaaaa
The program counter bits 0~11 are saved in the stack and the specified ad-
dress loaded into the program counter.
Stack ← PC+2
PC ← address
Clear carry flag
00101010
The carry flag is reset to zero.
CF ← 0
Decimal-Adjust accumulator
00110110
The accumulator value is adjusted to BCD (Binary Code Decimal), if the
contents of the accumulator is greater than 9 or CF (Carry flag) is one.
If ACC>9 or CF=1 then
ACC ← ACC+6, CF ← 1
else
ACC ← ACC, CF ← CF
Decrement accumulator
00111111
Data in the accumulator is decremented by one. Carry flag is not affected.
ACC ← ACC–1
Decrement register
0001nnn1
Data in the working register “Rn” is decremented by one. Carry flag is not
affected.
Rn ← Rn–1; Rn=R0,R1,R2,R3,R4, for nnn=0,1,2,3,4
Decrement data memory
00001101
Data in the data memory specified by the register pair “R1,R0” is decre-
mented by one. Carry flag is not affected.
M(R1,R0) ← M(R1,R0)–1
17
17th Nov ’98