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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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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