Zilog Z80380 - Manual (Page 162)

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Z380 ™
U SER ' S M ANUAL
DC-8297-03
Z ILOG
OUTDW
OUTPUT AND DECREMENT (WORD)
OUTDW
Operation: BC(15-0)
←
BC(15-0) - 1
(DE)
←
(HL)
HL
←
HL - 2
This instruction is used for block output of strings of data. During the I/O transaction the 32-
bit DE register is placed on the address bus.
First the BC register, used as a counter, is decremented by one. The word of data from the
memory location addressed by the HL register is loaded into the selected peripheral. The
HL register is then decremented by two, thus moving the pointer to the next source for the
output.
Flags: S: Unaffected
Z: Set if the result of decrementing BC is zero; cleared otherwise
H: Unaffected
V: Unaffected
N: Set
C: Unaffected
Addressing Execute
Mode Syntax Instruction Format Time Note
OUTDW 11101101 11101011 2+r+o