motorola Motorola M6800 Programming Reference Manual M68PRM(D) Nov76 free download

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M68PRM{D) Nov., 1976 M6800 PROGRAMMING REFERENCE MANUAL The information in this document has been carefully checked and is believed to be entirely reliable. However, no responsibility is assumed for inaccuracies. Furthermore, such information does not convey to the purchaser of the product described any license under the patent rights of Motorola, Inco or others. Motorola reserves the right to change specifications without notice. EXORciser, EXORdisk, and EXORtape are trademarks of Motorola Inc. First Edition Motorola, Inc. 1976 "All Rights Reserved" ii TABLE OF CONTENTS CHAPTER 1: INTRODUCTION 1-1 CHAPTER 2: HARDWARE DESCRiPTION 2-1 2.0 Introduction 2-1 2.1 The Basic Microcomputer Components 2-1 2.1.1 A Minimum System 2-1 2.1.1.1 MPU - Microprocessor Unit 2-2 2.1.1.2 ROM - 1024 x 8-Bit Read Only Memory 2-4 2.1.1.3 RAM - 128 x 8-Bit Static Random Access 2-4 2.1.1.4 PIA - Peripheral Interface Adapter 2-4 2.1.2 Expanding the Basic System 2-6 2.1.2.1 ACIA - Asynchronous Communications Interface Adapter 2-6 CHAPTER 3: PROGRAMMING THE M6800 MiCROPROCESSOR 3-1 3.0 Machine Code 3-1 3.1 Stack and Stack Pointer 3-1 3.2 Saving MPU Status 3-3 3.3 Interrupt Pointers 3-4 3.3.1 Reset (or Power On) 3-4 3.3.2 Non-Maskable Interrupt - NMI 3-5 3.3.3 Software Interrupt - SWI 3-5 3.3.4 Interrupt Request 3-5 3.3.5 Wait Instruction - WAI 3-6 3.3.6 Manipulation of the Interrupt Mask Bit 3-6 3.3.7 Special Programming Requirements 3-7 3.3.8 Look-Ahead Feature 3-7 3.3.9 Return from Interrupt - RTI 3-7 3.4 Subroutine Linkage 3-8 3.4.1 Call Subroutine - BSR or JSR 3-8 3.4.2 Return from Subroutine - RTS 3-8 3.5 Data Storage in the Stack