1. The bus of a computer is like the highway of a computer , Can you name the main functions and categories of the bus ?

answer :

function , Connect the parts of a computer together , It is usually used to connect CPU, Memory and IO equipment .

classification : On chip bus , system bus ; System bus can be divided into data bus , Address bus , Control bus .

2. What is the bus standard , Why bus standards are needed , What are the common bus standards now ?

answer :

The bus standard is used to standardize the system and each module , A standard for interconnection between modules .

With the bus standard , Different manufacturers can produce equipment according to the same standards and specifications , Achieve the purpose of interconnection .

Common standards :ISA,PCI,USB,PCIe.

3. It's often said "IO equipment ', "I","O" What are their abbreviations ?

answer :

IO The devices are Input and Output Abbreviation for

4. What kinds of common input devices can be divided into ?

answer :

Character input : keyboard .

Image input : mouse , Digital plate , Scanner .

5. What kinds of common output devices can be classified ?

answer :

Classification of output devices : screen , printer .

6. Common computer peripherals ( monitor , keyboard , mouse , printer ), What kind of equipment do they belong to ?

answer :

output , input , input , output .

7. I / O interface — What kind of work should be done , Can divide the line of interface into what line ?

answer :

Connect external devices with CPU Connect , Information exchange .

Line classification : data line , State line , Command line , Address line .

8. DMA What is the full name of ?

answer :

Direct memory access .

9. Program interruption and DMA comparison , What are the advantages and disadvantages ?

answer :

advantage : Program interrupt is easy to implement ,DMA High equipment cost .

inferiority : Frequent interruptions are required CPU, reduce CPU Processing efficiency of .

10. Can you clearly describe the hierarchy of computer memory ? What is the purpose of memory hierarchy ?

answer :

Memory hierarchy : cache , Main memory , Auxiliary deposit .

cache - Main memory to solve the problem of insufficient main memory speed , Main memory - Secondary storage is to solve the problem of insufficient main memory capacity .

11. What is the principle of locality , How does locality affect the design of computer storage system ?

answer :

Principle of locality : Time locality : A block of memory used may be reused in the near future ; Spatial locality : Memory in the vicinity of a used memory block may be used .

influence : Each layer of the computer memory hierarchy caches the next layer ( It's a little slower ) Part of the data .

12. What are the characteristics of each level of computer storage system ?

answer :

The faster the speed , The higher the cost ; leave CPU The further away , The slower the speed .

13. Computer auxiliary memory generally refers to computer hard disk , Do you know the physical structure of computer disks ?

answer :

understand , A disk usually has more than one disk , There is a magnetic head on each disk , The heads move synchronously . Each disk is divided into tracks ( cylinder ), a sector . Disk read time = Seeking truth + rotate + transmission .

14. What are the disk scheduling algorithms ? What are their characteristics ?

answer :

Disk scheduling algorithm :

First come, first served algorithm FIFO: Schedule according to the order of process requests to access the disk .

Shortest seek time SSTF: In request queue , Find the most recent service in progress .

Elevator algorithm ( Scanning algorithm )SCAN: Swing scanning algorithm , The direction of each movement is single , Only in or out .

Cyclic scanning algorithm C-SCAN: One way movement of magnetic head , After visiting the end of one end , Go back to the other end immediately .

LOOK and C-LOOK

15. The main memory of a computer generally refers to the computer memory , What are the characteristics of memory ?

answer :

Memory is CPU Direct addressable storage unit , Fast access , Generally used RAM storage . Data loss in case of power failure .

16. Please explain the concept : Main memory , Auxiliary deposit ,Cache,RAM,ROM?

answer :

Main memory : Direct to CPU Devices that provide storage , high speed , Power failure cannot be saved .

Auxiliary deposit : Generally refers to external memory , Like hard disk , CD and so on , This kind of memory can still store data after power failure .

Cache: cache , Located in CPU Between and memory .

RAM: Random access memory , Data loss due to power failure .

ROM: read-only memory , Cannot be modified or deleted after storage .

17. What is a word ? What are chunks ?

answer :

word : A binary unit in a storage unit , Word length is the number of digits in a word .

Word block : A set of words stored in a contiguous storage cell and treated as a unit .

18. The cache of a computer generally refers to Cache, Cache What hardware devices are generally located on the computer ?

answer :

On the motherboard or CPU upper .

19. — What indicators are used to evaluate main memory - Cache performance ?

answer :

hit rate , Access efficiency .

20. How is the hit rate defined ?

answer :

The number of times the cache was accessed / Total visits .

21. How is access efficiency defined ?

answer :

Time to access cache / Total visit time .

22. hypothesis CPU Execute a certain program, total visits Cache Hit 4800 second , Access to main memory 200 second , Known Cache The access cycle of 30ns, The access cycle of main memory is 150ns,
seek Cache- Average access time and efficiency of main memory system , How much performance has been improved ?

answer :

hit rate = 4800 / 5000 = 0.96

average access time   = 30ns * 0.96 + 150ns * 0.04 = 34.8ns

Access efficiency = 30/34.8 = 0.8621 = 86%

Improved (150-34.8)/150 * 100% = 76.8%

23. Predicate description LFU ,LRU ,FIFO The process of cache replacement algorithm .

answer :

LFU: Least use algorithm , Eliminate the most frequently used memory block .

LRU: Recent algorithms , Eliminate pages that have not been used recently .

FIFO: FIFO algorithm , The first memory block entered is replaced by the first one .

24. The instruction of computer is generally composed of operation code and address code , Then computer instructions can be classified into several types ?

answer :

Instruction type : Shift operation instruction , Data transfer instruction , Control instruction and arithmetic logic operation instruction .

25. What are the ways to address computer instruction data ?

answer :

Immediate addressing , Direct addressing , Indirect addressing .

26. What are the main components of a computer's arithmetic unit ? What about the controller ?

answer :

Composition of arithmetic unit :ALU, Status register , accumulator ( Data buffer ), General register .

Composition of controller : Program counter PC, control unit CU, Instruction register IR.

27. Please briefly describe the execution process of computer instructions .

answer :

It is mainly divided into taking instructions , Analysis instruction , Execute instruction .

from PC Get instruction address to MAR in , Control unit according to MAR Address in memory to get instructions , The retrieved instructions are placed in the MDR in ,MDR Give the instructions to the decoder ID Analysis , Then execute the instruction .

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