COP8SA-DM National Semiconductor, COP8SA-DM Datasheet - Page 95

• Manufacturer Part Number: COP8SA-DM
• Description: MODULE DEBUGGING FOR COP8SA
• Manufacturer: National Semiconductor

Specifications of COP8SA-DM

• Module/board Type: Debugger Module
• For Use With/related Products: Cop 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *COP8SA-DM

resume normal execution.
Transfer-of-Control Addressing Modes
Program instructions are usually executed in sequential order. However, Jump
instructions can be used to change the normal execution sequence. Several transfer-of-
control addressing modes are available to specify jump addresses.
A change in program flow requires a non-incremental change in the Program Counter
contents. The Program Counter consists of two bytes, designated the upper byte (PCU)
and lower byte (PCL). The most significant bit of PCU is not used, leaving 15 bits to
address the program memory.
Different addressing modes are used to specify the new address for the Program Counter.
The choice of addressing mode depends primarily on the distance of the jump. Farther
jumps sometimes require more instruction bytes in order to completely specify the new
Program Counter contents.
The available transfer-of-control addressing modes are:
The transfer-of-control addressing modes are described below. Each description includes
an example of a Jump instruction using a particular addressing mode, and the effect on
the Program Counter bytes of executing that instruction.
• Jump Relative
• Jump Absolute
• Jump Absolute Long
• Jump Indirect
Example:
Load Accumulator Indirect
LAID
Memory Location
Accumulator
041F Hex
Reg/Data
Memory
PCU
PCL
Contents
1F Hex
04 Hex
35 Hex
25 Hex
Before
Contents
04 Hex
36 Hex
25 Hex
25 Hex
After
COP8SAx7 MICROCONTROLLER
2-57