ZiLOG Z80380 User Manual page 106

Z
ILOG
IND
INPUT AND DECREMENT (BYTE)
IND
← (C)
Operation: (HL)
← B – 1
B
← HL – 1
HL
This instruction is used for block input of strings of data. During the I/O transaction the 32-
bit BC register is placed on the address bus. Note that the B register contains the loop count
for this instruction so that A15-A8 are not useable as part of a fixed port address.
First the byte of data from the selected peripheral is loaded into the memory location
addressed by the HL register. Then the B register, used as a counter, is decremented by
one. The HL register is then decremented by one, thus moving the pointer to the next
destination for the input.
S: Unaffected
Flags:
Z: Set if the result of decrementing B is zero; cleared otherwise
H: Unaffected
V: Unaffected
N: Set
C: Unaffected
Addressing
Mode Syntax
IND
5-72
Instruction Format
11101101 10101010
Z380
U ' M
SER S ANUAL
Execute
Time Note
2+i+w
DC-8297-03
™