DM-COP8/20D National Semiconductor, DM-COP8/20D Datasheet - Page 109

• Manufacturer Part Number: DM-COP8/20D
• Description: CABLE FOR DEBUG MODULE 20-DIP
• Manufacturer: National Semiconductor

Specifications of DM-COP8/20D

• Accessory Type: 20-DIP Target Cable
• For Use With/related Products: MetaLink Debug Module
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *DM-COP8/20D

Syntax:
Description:
Operation:
DRSZ REG#
Instruction
DRSZ REG#
This instruction decrements the contents of the selected memory regis-
ter (selected by #, where # = 0 to F) and places the result back in the
same register. If the result is zero, the next instruction is skipped. This
instruction is useful where it is desired to repeat an instruction sequence
a given number of times. The desired number of times that the instruc-
tion sequence is to be executed is placed in a register, and a DRSZ in-
struction with that register is coded at the end of the sequence followed
by a JP (Jump Relative) instruction that branches back to the start of
the instruction sequence. The JP branch-back instruction is executed
each time around the instruction sequence loop until the register count
is decremented down to zero, at which time the JP instruction is skipped
as the program branches (skips) out of the loop.
REG <- REG - 1
IF (REG - 1) = 0,
THEN SKIP NEXT INSTRUCTION
Register Direct (Implicit)
Addressing Mode
Instruction
Cycles
COP8SAx7 MICROCONTROLLER
3
Bytes Hex Op Code
1
C (REG#)
2-71