Motorola M68000 - Page 3

viii M68000 USER’S MANUAL MOTOROLA
TABLE OF CONTENTS (Continued)
Paragraph Page
Number Title Number
Section 4
8-Bit Bus Operations
4.1 Data Transfer Operations............................................................................. 4-1
4.1.1 Read Operations ...................................................................................... 4-1
4.1.2 Write Cycle ............................................................................................... 4-3
4.1.3 Read-Modify-Write Cycle.......................................................................... 4-5
4.2 Other Bus Operations............................................................................... 4-8
Section 5
16-Bit Bus Operations
5.1 Data Transfer Operations............................................................................ 5-1
5.1.1 Read Operations ..................................................................................... 5-1
5.1.2 Write Cycle .............................................................................................. 5-4
5.1.3 Read-Modify-Write Cycle......................................................................... 5-7
5.1.4 CPU Space Cycle.................................................................................... 5-9
5.2 Bus Arbitration .......................................................................................... 5-11
5.2.1 Requesting The Bus.............................................................................. 5-14
5.2.2 Receiving The Bus Grant ...................................................................... 5-15
5.2.3 Acknowledgment of Mastership (3-Wire Arbitration Only)..................... 5-15
5.3 Bus Arbitration Control.............................................................................. 5-15
5.4 Bus Error and Halt Operation.................................................................... 5-23
5.4.1 Bus Error Operation .............................................................................. 5-24
5.4.2 Retrying The Bus Cycle......................................................................... 5-26
5.4.3 Halt Operation ....................................................................................... 5-27
5.4.4 Double Bus Fault................................................................................... 5-28
5.5 Reset Operation........................................................................................ 5-29
5.6 The Relationship of DTACK, BERR, and HALT ......................................... 5-30
5.7 Asynchronous Operation .......................................................................... 5-32
5.8 Synchronous Operation ............................................................................ 5-35
Section 6
Exception Processing
6.1 Privilege Modes............................................................................................ 6-1
6.1.1 Supervisor Mode ...................................................................................... 6-2
6.1.2 User Mode ................................................................................................ 6-2
6.1.3 Privilege Mode Changes .......................................................................... 6-2
6.1.4 Reference Classification........................................................................... 6-3
6.2 Exception Processing................................................................................... 6-4
6.2.1 Exception Vectors .................................................................................... 6-4
6.2.2 Kinds Of Exceptions................................................................................. 6-5
6.2.3 Multiple Exceptions................................................................................... 6-8
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