Intel 8253 - Page 569

4/17/98 6-169 Addressing Modes and Data Types
XCH Exchange
Syntax: XCH dest, src
Operation: dest <--> src
Description: The data specified by the source and destination operands is exchanged.
Size: Byte-Byte, word-word.
Flags Updated: none
XCH Rd, Rs
Bytes: 2
Clocks: 5
Operation: (Rd) <--> (Rs)
Encoding:
XCH Rd, [Rs]
Bytes: 2
Clocks: 6
Operation: (Rd) <--> ((WS:Rs))
Encoding:
XCH Rd, direct
Bytes: 3
Clocks: 6
Operation: (Rd) <--> (direct)
Encoding:
byte 3: lower 8 bits of direct
0 1 1 0 SZ 0 0 0 d d d d s s s s
0 1 0 1 SZ 0 0 0 d d d d 0 s s s
1 0 1 0 SZ 0 0 0 d d d d 1 direct: 3 bits