ZiLOG Z80380 User Manual page 130

Z
ILOG
LDD
LOAD AND DECREMENT (BYTE)
LDD
Operation: (DE)
DE
HL
BC(15-0)
This instruction is used for block transfers of strings of data. The byte of data at the location
addressed by the HL register is loaded into the location addressed by the DE register. Both
the DE and HL registers are then decremented by one, thus moving the pointers to the
preceeding elements in the string. The BC register, used as a counter, is then decremented
by one.
Flags: S: Unaffected
Z: Unaffected
H: Cleared
V: Set if the result of decrementing BC is not equal to zero; cleared otherwise
N: Cleared
C: Unaffected
Addressing
Mode Syntax
LDD
5-96
← (HL)
← DE – 1
← HL – 1
← BC(15-0) – 1
Instruction Format
11101101 10101000
Execute
Time Note
3+r+w
Z380 ™
U ' M
SER S ANUAL
DC-8297-03