51 MCU Basics (2)

1. When the MCS-51 pin ALE is valid, it means that the (    low 8 bits    ) address is sent stably from the P0 port.

2. The stack of MCS-51 is  an area temporarily allocated in the (   on-chip  ) data memory by the software to fill in the stack pointer.  

3. When using 8751 and #EA=1, and the program memory address is less than (    1000H     ), the on-chip ROM is accessed.

4. In the MCS-51 system, when the #PSEN signal is valid, it means that the CPU wants to read information from the (    external program     ) memory.

5. MCS-51 has 4 groups of working registers, and their address range is (   00H~1FH   ).

6. The data memory in the range of 20H~2FH in the MCS-51 chip can be addressed by both byte and    bit     .

7.   When RS1 RS0=10 in PSW, the address of R2 is (    12H     ).

8.   When RS1 RS0=11 in PSW, the address of R2 is (    1AH     ).

9. After the microcontroller system is reset, (PSW) = 00H, so the current register of the on-chip RAM register area is the (    0    )th group, and the unit addresses of the 8 registers are (   00H   )~(   07H    ).

10. After reset, PC is (   0000H    ).

11. One machine cycle = (   12   ) oscillation periods = (    6    ) clock cycles.

12. The content of PC is (   the address of the instruction to be executed   ).

13. In the MCS-51 microcontroller, if a 6MHz crystal oscillator is used, one machine cycle is (    2us    ).

14. In the internal RAM, the bit address is 30H, and the byte address of the byte where the bit is located is (    26H   ).

15. If the content in A is 63H, then the value of the P flag is (    0    ).

16. After the 8051 microcontroller is reset, the address of the storage unit corresponding to R4 is (    04H  ). Because PSW = ( 00H  )  when powered on  , the current working register area is the (   0   )th group of working register area.      

17. When using the 8031 ​​chip, the #EA pin needs to be connected to a (    low    ) level because there is no (   program   ) memory inside the chip.

18. The lower 128 units of on-chip RAM can be divided into  three main parts: (working register area  ), (   bit addressing area   ) and (   user RAM area  ). 

19. To implement a subroutine call through stack operation, first push the contents of (    PC    ) into the stack to save the breakpoint; when the call returns, pop the stack again to restore the saved breakpoint to (    PC    ).

20. The addressing range of the MCS-51 microcontroller program memory is determined by the number of bits of the program counter PC. Since the PC of MCS-51 is 16 bits, its addressing range is (    64    ) KB.

21. The MCS-51 microcontroller has a total of (   32   ) registers in the on-chip RAM, which are divided into (   4   ) groups of registers, each with (8   ) units, and the register names are R0~R7.

22. When the model of the microcontroller is 8031/8032, its chip lead #EA must be connected to a (    low   ) level.