LD

The LD instruction is used to put the value from one place into another place.

Syntax

 LD N,M

puts M into N.

Allowed instructions
(across: M Down: N)

If x, it means allowed. If shaded in, it means not allowed.

	A	B	C	D	E	H	L	I	R	IXH	IXL	IYH	IYL	BC	DE	HL	SP	IX	IY	(BC)	(DE)	(HL)	(IX+N)	(IY+N)	N	NN	(NN)
A	x	x	x	x	x	x	x	x	x	x	x	x	x							x	x	x	x	x	x		x
B	x	x	x	x	x	x	x			x	x	x	x									x	x	x	x
C	x	x	x	x	x	x	x			x	x	x	x									x	x	x	x
D	x	x	x	x	x	x	x			x	x	x	x									x	x	x	x
E	x	x	x	x	x	x	x			x	x	x	x									x	x	x	x
H	x	x	x	x	x	x	x															x	x	x	x
L	x	x	x	x	x	x	x															x	x	x	x
I	x
R	x
IXH	x	x	x	x	x					x	x														x
IXL	x	x	x	x	x					x	x														x
IYH	x	x	x	x	x							x	x												x
IYL	x	x	x	x	x							x	x												x
BC																										x	x
DE																										x	x
HL																										x	x
SP																x		x	x							x	x
IX																										x	x
IY																										x	x
(BC)	x
(DE)	x
(HL)	x	x	x	x	x	x	x																		x
(IX+N)	x	x	x	x	x	x	x																		x
(IY+N)	x	x	x	x	x	x	x																		x
(NN)	x													x	x	x	x	x	x

Effects

No flags are altered except in the cases of the I or R registers.

In those cases, C is preserved, H and N are reset, and alters Z and S. P/V is set if interrupts are enabled, reset otherwise.

Uses

Use to load numbers into operands. They can either be numbers used in the code (usually 8-bits), or labels (usually 16-bits).

ld b,$05    ;Counter

ld hl,var    ;Variable label
ld a,(var)    ;Write data to var

T-States

r denotes 8-bit register.
rr represents a two byte register pair: BC, DE, HL, SP

r, r'	4
r,X	7
r,(hl)	7
r,(ix+X)	19
r,(iy+X)	19
a, (vc)	7
a, (de)	7
a, (XX)	13
(bc),a	7
(de),a	7
(XX),a	13
a, i	9
a, r	9
i, a	9
r, a	9
a, (BC)	7
(XX), a	13
rr,XX	10
ix, XX	14
iy, XX	14
hl, (XX)	20
ix, (XX)	20
iy, (XX)	20
(XX), hl	20
(XX), rr	20
(XX), ix	20
(XX), iy	20
sp, hl	6
sp, ix	10
sp, iy	10

See also

LDD,LDDR,LDI,LDIR

Source: http://www.zilog.com/appnotes_download.php?FromPage=DirectLink&dn=UM0080&ft=User%20Manual&f=YUhSMGNEb3ZMM2QzZHk1NmFXeHZaeTVqYjIwdlpHOWpjeTk2T0RBdmRXMHdNRGd3TG5Ca1pnPT0=