26. This program code will read data from port 0 and write it to port 2, and it will stop looping when bit 3 of port 2 is set:
STAT: MOV A, PO MOV P2,A JNB P2.3, STAT
27. Which of the following commands will move the value at port 3 to register 2?
28. The number of data registers is:
29. When the 8051 is reset and the EA line is LOW, the program counter points to the first program instruction in the:
30. The designs of a centigrade thermometer and a PWM speed-control circuit can be implemented by the 8051.
31. What is the difference between the 8031 and the 8051?
32. The I/O port that does not have a dual-purpose role is:
33. To interface external EPROM memory for applications, it is necessary to demultiplex the address/data lines of the 8051.
34. The following command will copy the accumulator to the location whose address is 23H:
MOV 23H,A
35. The special function registers can be referred to by their hex addresses or by their register names.
36. The contents of the accumulator after this operation
MOV A,#2BH
ORL A,00H
will be:
37. The following program will cause the 8051 to be stuck in a loop:
LOOP: MOV A, #00H JNZ LOOP
38. Which of the following commands will copy the contents of RAM whose address is in register 0 to port 1?
39. The statement LCALL READ passes control to the line labelled READ.
40. Which of the following commands will copy the contents of location 4H to the accumulator?
41. The microcontroller is useful in systems that have nonvariable programs for dedicated applications.
42. The total amount of external code memory that can be interfaced to the 8051 is:
43. The ADC0804 has ________ resolution.
44. A HIGH on which pin resets the 8051 microcontroller?
45. An alternate function of port pin P3.1 in the 8051 is:
46. Which of the following instructions will move the contents of the accumulator to register 6?
47. The following command will rotate the 8 bits of the accumulator one position to the left:
RL A
48. An alternate function of port pin P3.0 (RXD) in the 8051 is:
49. Analog output current must be converted into a usable voltage. To perform this current-to-voltage conversion a 700 op amp may be used.
50. A Celsius thermometer is an application for the 8051 microcontroller.