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CONTENTS
6.3.4 Interrupt Acknowledge Cycle ..................................................................................6-23
6.3.5 Halt/Shutdown Cycle ...............................................................................................6-26
6.3.6 Refresh Cycle .........................................................................................................6-28
6.3.7 BS8 Cycle ...............................................................................................................6-31
6.3.7.1 Write Cycles .......................................................................................................6-31
6.3.7.2 Read Cycles .......................................................................................................6-31
6.4 BUS LOCK................................................................................................................... 6-34
6.4.1 Locked Cycle Activators ..........................................................................................6-34
6.4.2 Locked Cycle Timing ...............................................................................................6-34
6.4.3 LOCK# Signal Duration ...........................................................................................6-35
6.5 EXTERNAL BUS MASTER SUPPORT (USING HOLD, HLDA).................................. 6-35
6.5.1 HOLD/HLDA Timing ................................................................................................6-36
6.5.2 HOLD Signal Latency .............................................................................................6-37
6.6 DESIGN CONSIDERATIONS...................................................................................... 6-38
6.6.1 Interface To Intel387™ SX Math Coprocessor .......................................................6-38
6.6.1.1 System Configuration .........................................................................................6-39
6.6.1.2 Software Considerations ....................................................................................6-40
6.6.2 SRAM/FLASH Interface ..........................................................................................6-41
6.6.3 PSRAM Interface ....................................................................................................6-42
6.6.4 Paged DRAM Interface ...........................................................................................6-43
6.6.5 Non-Paged DRAM Interface ...................................................................................6-44
CHAPTER 7
SYSTEM MANAGEMENT MODE
7.1 SYSTEM MANAGEMENT MODE OVERVIEW............................................................. 7-1
7.2 SMM HARDWARE INTERFACE................................................................................... 7-1
7.2.1 System Management Interrupt Input (SMI#) .............................................................7-1
7.2.2 SMM Active Output (SMIACT#) ................................................................................7-2
7.2.3 System Management RAM (SMRAM) ......................................................................7-2
7.3 SYSTEM MANAGEMENT MODE PROGRAMMING AND CONFIGURATION............. 7-3
7.3.1 Register Status During SMM .....................................................................................7-3
7.3.2 System Management Interrupt ..................................................................................7-4
7.3.2.1 SMI# Priority .........................................................................................................7-7
7.3.2.2 System Management Interrupt During HALT Cycle .............................................7-8
7.3.2.3 HALT Restart .......................................................................................................7-9
7.3.2.4 System Management Interrupt During I/O Instruction ..........................................7-9
7.3.2.5 I/O Restart ..........................................................................................................7-10
7.3.3 SMM Handler Interruption .......................................................................................7-10
7.3.3.1 Interrupt During SMM Handler ...........................................................................7-10
7.3.3.2 HALT During SMM Handler ................................................................................7-11
7.3.3.3 Idle Mode and Powerdown Mode During SMM ..................................................7-12
7.3.3.4 SMI# During SMM Operation .............................................................................7-12
7.3.4 SMRAM Programming ............................................................................................7-12
7.3.4.1 Chip-select Unit Support for SMRAM .................................................................7-12