Intel 8XC251SQ, 8XC251SA XCH A,byte, XCH A,@R0, Binary Mode = Encoding Source Mode = Encoding

8XC251SA, SB, SP, SQ USER’S MANUAL

	Binary Mode	Source Mode
Bytes:	2	1
States (2 bytes):	11	10
States (4 bytes):	16	15

[Encoding]

1 0 1 1

1 0 0 1

Hex Code in: Binary Mode = [A5][Encoding]

Source Mode = [Encoding]

Operation: TRAP

SP ← SP – 2

(SP) ← PC

PC ← (0FF007BH)

XCH A,<byte>

Function: Exchange accumulator with byte variable

Description: Loads the accumulator with the contents of the specified variable, at the same time writing the original accumulator contents to the specified variable. The source/destination operand can use register, direct, or register-indirect addressing.

Flags:

CY	AC	OV	N	Z
—	—	—	—	—

Example: R0 contains the address 20H, the accumulator contains 3FH (00111111B) and on-chip RAM location 20H contains 75H (01110101B). After executing the instruction

XCH A,@R0

RAM location 20H contains 3FH (00111111B) and the accumulator contains 75H (01110101B).

Variations

XCH A,dir8

Binary Mode Source Mode

Bytes:

States:

[Encoding]

Hex Code in:

Operation:

	2		2
	3†		3†
†If this instruction addresses a port (Px, x = 0–3), add 2 states.
1 1 0 0		0 1 0 1		direct addr

Binary Mode = [Encoding]

Source Mode = [Encoding]

XCH

(A) → ← (dir8)

A-130