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MULTIPLE CHOICE QUESTIONS

Consider 8051 family microcontroller in the following questions

  1. (a) A, B and PSW

    (b) A is accumulator, only B and PSW

    (c) PSW is not among ones, which

    (d) None of the A, B and PSW are the special functions registers

  2. Number of ports used in an expanded mode are:

    (a) two

    (b) three

    (c) four in case of additional devices present in a family member

    (d) depends according to the use of external program memory or on use of external as well as data memory

  3. RS0 and RS1:

    (a) are not in the PSW as these are not the flags

    (b) are in the register sets (banks)

    (c) are the bits-4 and 5, respectively, for selecting the register bank in the PSW

    (d) are the bits-3 and 4, respectively, for selecting the register bank in the PSW. Note: Bit 7 is C (carry or borrow) flag

  4. (a) We can use a common memory chip for the program and data, if we join the and pins

    (b) If we join the and pins, the 8051 will not save the program at external memory

    (c) If we connect pin to Vcc then we cannot use the external program memory

    (d) The 8-bit address of a byte as 0x00 refer to internal RAM if = 1 and external RAM if = 0

  5. Reset pin is:

    (a) active when connected to 1

    (b) active for a few cycles only

    (c) active when connected to 0

    (d) active only on watchdog timer reset

  6. (a) Port P0 can be used as an output only because it is used as AD0-AD7 in the expanded mode:

    (b) All port bits can be used as input or output in single-chip mode

    (c) A port bit can be used as an input after writing 0 at it

    (d) Two ports P0 and P2 are the output ports and P1 and P3 are the input ports:

  7. Bit address 0x00 and byte address 0x00 are for the:

    (a) Bit 0 at 0x20 and the byte at 0x00 in the internal RAM

    (b) Bit 0 at 0x00 and the byte at 0x00 in the internal RAM

    (c) Bit = 0 in a SFR and the byte = 0x00

    (d) Bit 0 at 0x20 and byte at 0x00, respectively

  8. TH1, TL1, TH0 and TL0 SFRs are at the addresses:

    (a) 0x8D, 0x8C, 0x8B and 0x8A

    (b) 0xAD, 0xAB, 0xAC and 0xAA

    (c) 0x8D, 0x8B, 0x8C and 0x8A

    (d) not between 0x80 and 0xFF as these are not the SFRs

  9. Mode bits M1 and M0 can:

    (a) be set as 11 at TMOD.5 and TMOD.4 and get assigned to TH0 as an 8-bit timer

    (b) be set as 00 only

    (c) can be set as 00 and 10 only

    (d) not be set as 11 at TMOD.5 and TMOD.4 because timer 1 does not function in mode 3

  10. Timer 1 runs and timer 0 stops:

    (a) when TCON.6 = 1 and TCON.4 = 0

    (b) when TCON.4 = 0 and TCON.5 = 1

    (c) when TCON.7 = 1 and TCON.5 = 0

    (d) when TCON all bits are 1s

  11. (a) Synchronous mode of operation of serial interface can either be to transmit or receive at a given instant

    (b) asynchronous mode of operation of serial interface can only either be transmit or receive at a given instant

    (c) synchronous and asynchronous mode of operation of serial interface can be transmit and receive at a given instant

    (d) only asynchronous 10T period and 11T periods exist in the serial interface using TB8 and RB8, bits

  12. When SM2 is set to:

    (a) 1, it facilitates the multiprocessor communication in case of mode 1 and 3 (variable baud rate serial UART mode)

    (b) 1, it facilitates sending the address for the multiprocessor communication in case of mode 2 and 3 (total 11 bit serial UART mode)

    (c) 0, it facilitates the multiprocessor communication in case of mode 2 and 3 (total 11 bit serial UART mode)

    (d) 0, it facilitates the multiprocessor communication in case of mode 0 only (synchronous communication mode)

  13. If a period is 0.33 ms between the serial bits, we can transfer in one second when SCON sets for mode 2:

    (a) 300 characters

    (b) 275 only

    (c) 30 characters

    (d) 272 characters

  14. At the RS232C because of the need to provide a margin for the attenuation and noise pickups:

    (a) 0 means + 3V down to + 25V

    (b) 0 means + 5V down to + 25V

    (c) 1 means + 3V down to + 25V

    (d) 1 means + 5 V down to + 12V

  15. IP.4 is set to 1 in the interrupt priority register:

    (a) synchronous serial communication mode priority becomes highest

    (b) timer T1 priority becomes highest

    (c) interface serial communication mode priority becomes highest

    (d) synchronous serial communication mode priority becomes lowest

  16. If IP register has been set as 0x00 then:

    (a) INT1 has the highest priority

    (b) INT0 has the highest and serial interface as the lowest priority

    (c) timer overflows have the highest priorities

    (d) there is no priority, interrupt processes in the order of its occurrence


  

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