
TABLE OF CONTENTS
iv
EPSON
Bus Operation....................................................................................................................................................B-II-4-14
Data Arrangement in Memory.......................................................................................................B-II-4-14
Bus Operation of External Memory.............................................................................................B-II-4-14
Bus Clock.............................................................................................................................................................B-II-4-18
Bus Speed Mode ...............................................................................................................................B-II-4-19
Bus Clock Output ...............................................................................................................................B-II-4-19
Bus Cycles in External System Interface ................................................................................................B-II-4-20
SRAM Read Cycles...........................................................................................................................B-II-4-20
SRAM Write Cycles ...........................................................................................................................B-II-4-22
Burst ROM Read Cycles .................................................................................................................B-II-4-24
DRAM Direct Interface....................................................................................................................................B-II-4-25
Outline of DRAM Interface..............................................................................................................B-II-4-25
DRAM Setting Conditions...............................................................................................................B-II-4-26
DRAM Read/Write Cycles...............................................................................................................B-II-4-29
DRAM Refresh Cycles .....................................................................................................................B-II-4-32
Releasing External Bus .................................................................................................................................B-II-4-33
Power-down Control by External Device ................................................................................................B-II-4-34
I/O Memory of BCU .........................................................................................................................................B-II-4-35
II-5 ITC (Interrupt Controller)...................................................................................B-II-5-1
Outline of Interrupt Functions.........................................................................................................................B-II-5-1
Maskable Interrupts.............................................................................................................................B-II-5-1
Interrupt Factors and Intelligent DMA...........................................................................................B-II-5-4
Nonmaskable Interrupt (NMI)..........................................................................................................B-II-5-4
Interrupt Processing by the CPU....................................................................................................B-II-5-4
Clearing Standby Mode by Interrupts...........................................................................................B-II-5-4
Trap Table.............................................................................................................................................................B-II-5-5
Control of Maskable Interrupts ......................................................................................................................B-II-5-6
Structure of the Interrupt Controller...............................................................................................B-II-5-6
Processor Status Register (PSR)...................................................................................................B-II-5-6
Interrupt Factor Flag and Interrupt Enable Register...............................................................B-II-5-7
Interrupt Priority Register and Interrupt Levels .........................................................................B-II-5-9
IDMA Invocation................................................................................................................................................B-II-5-10
HSDMA Invocation...........................................................................................................................................B-II-5-12
I/O Memory of Interrupt Controller .............................................................................................................B-II-5-13
Programming Notes.........................................................................................................................................B-II-5-25
II-6 CLG (Clock Generator)......................................................................................B-II-6-1
Configuration of Clock Generator.................................................................................................................B-II-6-1
I/O Pins of Clock Generator ...........................................................................................................................B-II-6-2
High-Speed (OSC3) Oscillation Circuit.......................................................................................................B-II-6-2
PLL...........................................................................................................................................................................B-II-6-3
Controlling Oscillation.......................................................................................................................................B-II-6-3
Setting and Switching Over the CPU Operating Clock.........................................................................B-II-6-4
Power-Control Register Protection Flag....................................................................................................B-II-6-5
Operation in Standby Mode ...........................................................................................................................B-II-6-5
I/O Memory of Clock Generator....................................................................................................................B-II-6-6
Programming Notes...........................................................................................................................................B-II-6-9