计算机专业英语教程 教学课件 作者桑莉君 练习答案.docVIP

Unit 1 1． (1) D (2) A (3) B (4) D (5) B (6) A (7) B (8) D (9) C (10)A 2． (1) D (2) E (3) A (4) C (5) B (6) G (7) F Unit 2 1. Describe the organization of basic computer systems. A computer generally consists of three subsystems: the CPU, memory, and the input/output subsystem. These subsystems communicate with each other using buses. The processor sends out the address to be accessed in memory or the address of the I/O device via the address bus. The data bus carries data between the subsystems. Information sent on the control bus coordinates all data transfers. 2. How does a processor process an instruction? To process an instruction, the processor goes through an instruction cycle. This, in turn, consists of cycles to fetch an instruction from memory, decode the instruction, and execute the instruction. All instructions are fetched and decoded in the same way, but the execute cycle is different for every instruction. 3. How many sections are there in a CPU, and what are their functions? The CPU has three sections: the register section is used for data storage. It contains the registers of the processor’s ISA as well as other registers not directly accessible by the programmer. The arithmetic/logic unit performs computations on data with the CPU. Since it must complete its operations within a single clock cycle, it is constructed using only combinatorial logic. The control unit outputs signals to control the rest of the processor. By outputting the control signals in the correct order, it causes the processor to fetch, decode, and execute instructions. 4. How many types of memory chips are used in computer design, and what are their main features? There are several types of memory chips used in computer design. The data in read only memory chips, including ROM, PROM, EPROM, and EEPROM, is fixed; their data does not change, and remains valid when the computer is turned off. The computer can modify the contents of random access memory,