计算机导论-第5章-计算机组成

Knowledge point:

5.1. three subsystems that make up a computer 5.2. functionality of each subsystem

5.3. memory addressing and calculating the number of bytes 5.4. addressing system for input/output devices.

5.5. the systems used to connect different components together.

Multiple-choice Questions

39. The ___ is a computer subsystem that performs operations on data.( Knowledge point 5.1) a. CPU b. memory c. I/O hardware

d. none of the above

40. ____ is a stand-alone storage location that holds data temporarily. ( Knowledge point 5.1) a. An ALU b. A register c. A control unit d. A tape drive

41. ____ is a unit that can add two inputs. ( Knowledge point 5.2) a. An ALU b. A register c. A control unit d. A tape drive

42. A register in a CPU can hold ____.( Knowledge point 5.2) a. data

b. instructions

c. program counter values d.all of the above

43. A control unit with five wires can define up to ____ operations. ( Knowledge point 5.2) a. 5 b. 10 c. 16 d. 32

44. A word is ____ bits. ( Knowledge point 5.3) a. 8 b. 16

c. 32

d. any of the above

45. If the memory address space is 16 MB and the word size is 8 bits, then ____ bits are needed to access each word. ( Knowledge point 5.3) a. 8 b. 16 c. 24 d.32

46. The data in ____ are erased if the computer is powered down. ( Knowledge point 5.5.3) a. RAM b. ROM

c. a tape drive d. a CD-ROM

47. ____ is a memory type with capacitors that need to be refreshed periodically. ( Knowledge point 5.3) a. SRAM b. DRAM c. ROM

d. all of the above

48. ____ is a memory type with traditional flip-flop gates to hold data. ( Knowledge point 5.3) a. SRAM b. DRAM c. ROM

d. all of the above

49. There are ____ bytes in 16 terabytes. ( Knowledge point 5.3) a.b. c.d.

50. ____ can be programmed and erased using electronic impulses but can remain in a computer during erasure. ( Knowledge point 5.3) a. ROM b. PROM c. EPROM d. EEPROM

51. ____ is a type of memory in which the user, not the manufacturer, stores programs that cannot be overwritten. ( Knowledge point 5.3) a. ROM

b. PROM c. EPROM d. EEPROM

52. CPU registers should have ____ speed memory. ( Knowledge point 5.3) a. high b. medium c. low

d. any of the above

53. Main memory in a computer usually consists of large amounts of ____ speed memory. ( Knowledge point 5.3) a. high b. medium c. low

d. any of the above

. The ____ memory contains a copy of a portion of main memory. ( Knowledge point 5.3) a. CPU b. cache c. main d. ROM

55. The ____ is nonstorage I/O device. ( Knowledge point 5.4) a. keyword b. monitor c. printer

d. all of the above

56.A ____ is an optical storage device. ( Knowledge point 5.4) a. CD-ROM b. CD-R c. CD-RM

d. all of the above

57. The ____ is a storage device in which the manufacturer writes information to the disc. ( Knowledge point 5.4) a. CD-ROM b. CD-R c. CD-RM

d. all of the above

58. The ____ is a storage device in which the user can writes information only once to the disc. ( Knowledge point 5.4) a. CD-ROM b. CD-R c. CD-RM

d. all of the above

59. The ____ is a storage device that can undergo multiple writings and erasings. ( Knowledge point 5.4)

a. CD-ROM b. CD-R c. CD-RM

d. all of the above

60. The smallest storage area on a magnetic disk that can be accessed at one time is a ____.( Knowledge point 5.4) a. track b. sector c. frame d. head

61. For a magnetic disk, the ____ time is the time it takes for the read/write head to move to the desired track where the data are stored. ( Knowledge point 5.4) a. rotation b. seek c. transfer d. location

62. Polycarbonate resin is used in ____ . ( Knowledge point 5.4) a. CD-ROMs b. CD-Rs c. CD-RWs

d. all of the above

63. In a ____, a high-power laser beam simulates pits in an alloy of silver, indium, antimony, and tellurium. ( Knowledge point 5.4) a. CD-ROM b. CD-R c. CD-RM

d. all of the above

. In a ____, a high-power laser beam simulates pits in the dye layer. ( Knowledge point 5.4) a. CD-ROM b. CD-R c. CD-RM

d. all of the above

65. Which optical storage device has the highest capacity ? ( Knowledge point 5.4) a. CD-ROM b. CD-R c. CD-RM d. DVD

66. In a DVD, a ____ beam reads the disk. ( Knowledge point 5.4) a. high-power laser b. infrared c. red laser d. blue laser

67. A ____ bus connects the CPU and memory. ( Knowledge point 5.5)

a. data b. address c. control

d. all of the above

68. If the word size is 2 bytes, a data bus with ____ wires is needed. ( Knowledge point 5.5) a. 2 b. 4 c. 8 d. 16 69. If the memory has

words, the address bus needs to have ____ wires.

( Knowledge point 5.5) a. 8 b. 16 c. 32 d.

70. A control bus with eight wires can define ____ operations. ( Knowledge point 5.5) a. 8 b. 16 c. 256 d. 512

71. The ____ controller features a parallel interface and daisy-chained connection for I/O devices. ( Knowledge point 5.5) a. SCSI

b. Fire Wire c. USB d. IDE

72. The ____ controller is a serial device that connects slow devices such as the keyboard and mouse to the computer. ( Knowledge point 5.5) a. SCSI

b. Fire Wire c. USB d. IDE

73. The ____ controller is a high-speed serial interface that transfers data in packets. ( Knowledge point 5.5) a. SCSI

b. Fire Wire c. USB d. IDE

74. The three steps in the running of a program on a computer are performed ____ in this specific order. ( Knowledge point 5.5) a. fetch, execute, and decode b. fetch, execute, and fetch

c. fetch, decode, and execute d. decode, fetch, and execute

75. In the ____ method to synchronize the operation of the CPU with the I/O device ,the I/O device informs the CPU when it is ready for data transfer. ( Knowledge point 5.5) a. programmed I/O b. interrupt-driven I/O c. DMA

d. isolated I/O

76. In the ____ method to synchronize the operation of the CPU with the I/O device, the CPU is idle until the I/O operation is finished. ( Knowledge point 5.5) a. programmed I/O b. interrupt-driven I/O c. DMA

d. isolated I/O

77. In the ____ method to synchronize the operation of the CPU with the I/O device, a large block of data can be passed from an I/O device to memory directly. ( Knowledge point 5.5) a. programmed I/O b. interrupt-driven I/O c. DMA

d. isolated I/O

Review questions:

1. What are the three subsystems that make up a computer?(Knowledge point 5.1) Answer: the CPU, main memory, and the input/output (I/O) subsystem. 2. What are the parts of a CPU? (Knowledge point 5.1)

Answer: The CPU performs operations on data and has a ALU, a control unit, and a set of registers.

3. What‘s the function of the ALU? (Knowledge point 5.2) Answer: The ALU performs arithmetic and logical operations.

Exercises:

78. A computer has MB of memory. Each word is 4 bytes. How many bits are needed to address each single word in memory? (Knowledge point 5.3) Solution:

The memory address space is MB, that is 2 raised to the power 26. The size of each word in bytes is 2 raised to the power 2. So we need 24(subtract 2 from 26) bits to address each single word in memory.

79. How many bytes of memory are needed to store a full screen of data if the screen is made of 24 lines with 80 characters in each line? The system uses ASCII code, with

each ASCII character store as a byte. (Knowledge point 5.3) Solution:

The quantity of bytes in a full screen is 1920 (24*80) while the system uses ASCII code with each ASCII character store as a byte. So we need 1920 bytes of memory to store the full screen of data.

80. An imaginary computer has four data registers(R0 to R3), 1024 words in memory, and 16 different instructions(add, subtract, etc.). What is the minimum size of an instruction in bits if a typical instruction uses the following format: add 565 R2. (Knowledge point 5.5) Solution:

The number of data registers in this computer is 4, that is 2 raised to the power 2. The number of words in this computer is 1024, that is 2 raised to the power 10. The number of instructions in this computer is 16, that is 2 raised to the power 4. So the minimum size of an instruction in bits is 16 (2+10+4) bits.

81. If the computer in Exercise 80 uses the same size of word for data and instructions. What is the size of each data register? (Knowledge point 5.5) Solution:

The size of an instruction in bits is 16. Data size is the same with that of an instruction. So 16 is the size of each data register.

82. What is the size of the instruction register of the computer in Exercise 80? (Knowledge point 5.5) Solution:

The size of an instruction in bits is 16. So the size of the instruction register of the computer is also 16.

83. What is the size of the program counter of the computer in Exercise 80? (Knowledge point 5.5) Solution:

The number of words in this computer is 1024, that is 2 raised to the power 10. So the size of the program counter of the computer is 10.

84. What is the size of the data bus in Exercise 80? (Knowledge point 5.5) Solution:

Data size of this computer in bits is 16. So the size of the data bus is 16.

85. What is the size of the address bus in Exercise 80? (Knowledge point 5.5) Solution:

The number of words in this computer is 1024, that is 2 raised to the power 10. So the the size of the address bus is 10.

86. What is the minimum size of the control bus in Exercise 80? (Knowledge point

5.5)

Solution:

There are 2 control actions(read and write to memory) at most. So the minimum size of the control bus is 1.

87. A computer uses isolated I/O addressing. Memory has 1024 words. If each controller has 16 registers, how many controllers can be accessed by this computer? (Knowledge point 5.4) Solution:

Memory has 1024 words. So the address space is 1024. Each controller has 16 registers. Then we get (divide 16 by 1024)controllers which can be accessed by this computer.

88. A computer uses memory-mapped I/O addressing. The address bus uses 10 lines. If memory is made of 1000 words, how many four-register controllers can be accessed by this computer? (Knowledge point 5.4) Solution:

The address bus uses 10 lines. So, the address space is 1024(2 raised to the power 10). The memory is made of 1000 words and each controller has four registers. Then we get (1024-1000)/4 = 6 four-register controllers which can be accessed by this computer.