KS57C2308/P2308/C2316/P2316
SAM47 INSTRUCTION SET
5-91
XCHD
— Exchange and Decrement
XCHD
dst,src
Operation:
Operand
Operation Summary
Bytes
Cycles
A,@HL
Exchange A and data memory contents; decrement
contents of register L and skip on borrow
1
2 + S
Description:
The instruction XCHD exchanges the contents of the accumulator with the RAM location
addressed by register pair HL and then decrements the contents of register L. If the content of
register L is 0FH, the next instruction is skipped. The value of the carry flag is not affected.
Operand
Binary Code
Operation Notation
A,@HL
0
1
1
1
1
0
1
1
A
↔
(HL), then L
←
L–1;
skip if L = 0FH
Example:
Register pair HL contains the address 20H and internal RAM location 20H contains the value
0FH:
LD
HL,#20H
LD
A,#0H
XCHD
A,@HL
; A
←
0FH and L
←
L – 1, (HL)
←
"0"
JPS
XXX
; Skipped since a borrow occurred
JPS
YYY
; H
←
2H, L
←
0FH
YYY
XCHD
A,@HL
; (2FH)
←
0FH, A
←
(2FH), L
←
L – 1 = 0EH
•
•
•
The “JPS YYY” instruction is executed since a skip occurs after the XCHD instruction.
Summary of Contents for KS57C2308
Page 30: ...ADDRESS SPACES KS57C2308 P2308 C2316 P2316 2 22 NOTES ...
Page 168: ...SAM47 INSTRUCTION SET KS57C2308 P2308 C2316 P2316 5 94 NOTES ...
Page 170: ......
Page 206: ...POWER DOWN KS57C2308 P2308 C2316 P2316 8 8 NOTES ...
Page 210: ...RESET KS57C2308 P2308 C2316 P2316 9 4 NOTES ...
Page 222: ...I O PORTS KS57C2308 P2308 C2316 P2316 10 12 NOTES ...
Page 272: ...LCD CONTROLLER DRIVER KS57C2308 P2308 C2316 P2316 12 24 NOTES ...
Page 280: ...SERIAL I O INTERFACE KS57C2308 P2308 C2316 P2316 13 8 NOTES ...
Page 294: ...MECHANICAL DATA KS57C2308 P2308 C2316 P2316 15 2 NOTES ...
Page 310: ...KS57P2308 P2316 OTP KS57C2308 P2308 C2316 P2316 16 16 NOTES ...
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