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CHAPTER 2 CPU
2.7.4
Program Counter (PC)
The PC register is a 16-bit counter that indicates the low-order 16 bits of the memory
address of an instruction code to be executed by the CPU. The high-order eight bits of
the address are indicated by the PCB. The PC register is updated by a conditional
branch instruction, subroutine call instruction, interrupt, or reset. The PC register can
also be used as a base pointer for operand access.
■
Program Counter (PC)
Figure 2.7-10 shows the program counter.
Figure 2.7-10 Program Counter
PCB
PC
FEH
ABCDH
FEABCDH
Next instruction to be executed
Summary of Contents for MB90390 Series
Page 2: ......
Page 4: ......
Page 17: ...xiii APPENDIX D List of Interrupt Vectors 690 INDEX 695 ...
Page 18: ...xiv ...
Page 132: ...104 CHAPTER 5 CLOCKS ...
Page 152: ...124 CHAPTER 6 CLOCK MODULATOR ...
Page 210: ...182 CHAPTER 11 TIME BASE TIMER ...
Page 218: ...190 CHAPTER 12 WATCHDOG TIMER ...
Page 264: ...236 CHAPTER 14 16 BIT RELOAD TIMER WITH EVENT COUNT FUNCTION ...
Page 274: ...246 CHAPTER 15 WATCH TIMER ...
Page 306: ...278 CHAPTER 17 DTP EXTERNAL INTERRUPTS ...
Page 338: ...310 CHAPTER 18 8 10 BIT A D CONVERTER ...
Page 364: ...336 CHAPTER 19 UART0 UART1 ...
Page 398: ...370 CHAPTER 20 UART2 UART3 Figure 20 5 2 ORE Set Timing Receive data RDRF ORE ...
Page 432: ...404 CHAPTER 20 UART2 UART3 ...
Page 482: ...454 CHAPTER 22 SERIAL I O ...
Page 560: ...532 CHAPTER 24 STEPPING MOTOR CONTROLLER ...
Page 582: ...554 CHAPTER 27 ROM MIRRORING MODULE ...
Page 632: ...604 CHAPTER 29 EXAMPLES OF SERIAL PROGRAMMING CONNECTION ...
Page 722: ...694 APPENDIX ...
Page 723: ...695 INDEX The index follows on the next page This is listed in alphabetic order ...
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