Motorola MC68HC05RC16, MC68HC05RC8 Section 3. Central Processor Unit

General Release Specification — MC68HC05RC16

Section 3. Central Processor Unit

3.1 Contents

3.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

3.3 Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

3.4 Index Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

3.5 Condition Code Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

3.6 Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

3.7 Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

3.2 Introduction

This section describes the registers of the MC68HC05RC16 central processor unit (CPU). The MCU contains five registers as shown in Figure 3-1. The interrupt stacking order is shown in Figure 3-2.

						7									0
										A						ACCUMULATOR
						7									0
										X						INDEX REGISTER
13															0
							PC									PROGRAM COUNTER
13						7									0
0	0	0	0	0	0	1		1			SP					STACK POINTER
												CCR
									H		I	N	Z	C		CONDITION CODE REGISTER

Figure 3-1. Programming Model

MC68HC05RC16 — Rev. 3.0		General Release Specification
MOTOROLA	Central Processor Unit	33