Instruction Set

Instruction Types

10.3.8 Relative

Relative addressing is only for branch instructions. If the branch condition is true, the CPU finds the effective branch destination by adding the signed byte following the opcode to the contents of the program counter. If the branch condition is not true, the CPU goes to the next instruction. The offset is a signed, two’s complement byte that gives a branching range of –128 to +127 bytes from the address of the next location after the branch instruction.

When using the Motorola assembler, the programmer does not need to calculate the offset, because the assembler determines the proper offset and verifies that it is within the span of the branch.

10.4 Instruction Types

The MCU instructions fall into the following five categories:

•Register/Memory Instructions

•Read-Modify-Write Instructions

•Jump/Branch Instructions

•Bit Manipulation Instructions

•Control Instructions

MC68HC05RC16 — Rev. 3.0

 

General Release Specification

 

 

 

MOTOROLA

Instruction Set

89