Computer hardware
CPU
CPU (Central Processing Unit) operator = (the ALC) + + register controller, the main task is to perform a data operation and process control.
Key performance indicators comprises a CPU clock speed, word length, cache capacity, instruction set.
Frequency : the CPU clock frequency, i.e., a digital pulse oscillation speed, typically in units of GHz (1GHz = 1000MHz)
Word size : the number of bits of the CPU can be processed simultaneously. The current 64-bit CPU is generally
- 4004 intel (1971): The first commercial microprocessor (not equal to the first CPU!), 4 position, 5 million instructions per second, 108KHz, 2300 transistors.
- Texas Instruments TMX 1795: The first 8 microprocessor.
- Intel 8086 (1978): The first 16-bit microprocessor
Memory
The CPU \ (\ Longleftrightarrow \) a main memory (internal) \ (\ Longleftrightarrow \) a secondary memory (outer)
Within: the cache memory (the Cache)> random memory (RAM, to power loss)> read-only memory (a ROM, power is not lost, can not be modified)
See the distance and speed of the CPU, the register> inside> outer
The following statement about computer memory which is correct:
The correct answer: BD Your answer: AD (error)
A random access memory (RAM) means that when the program runs, each assigned to a specific memory location of the program is not random definite.
A general personal computer B at the same time only load / store a specific memory cell.
C includes a main memory strictly computer memory (memory), three partial cache (Cache) and registers (register).
D1MB memory generally refers to the size of 1024 * 1024 bytes of memory.Refers to when the data in the memory is read or written, the time required for the position where this information is written or
Regardless of the position. relatively
Bus Architecture
~ ~ Address ~ Data bus
The maximum memory capacity accessible to the central processing unit CPU depends on the address bus
Signals transmitted on the bus 8. The computer system ()
A. There address signal and the control signal B. The data signal, control signal and the address signal
C. D. control and data signals for the data signal and address signal
Answer: C, system bus there are the three signal empathy
Computer Performance
Word: at the same time deal with binary digits (Unit: bit, bit)
Clocked
Computer instruction
Computer instruction: instruction is a set of binary codes, a predetermined step operation program executed by a computer.
An instruction by the operation code and operands , the former predetermined instruction to complete the operation, which is the operation target directed.
Von Neumann
- Computerized data and instructions with all binary represents
- Sequence program execution, while the computer, and the data processing program to be executed is first stored in the main memory (RAM), the computer executes the program, automatically and sequentially fetching instructions from the main memory is performed in a one, which a concept referred to as sequential execution of the program.
- Computer hardware by the operator, controller, memory, input devices and output devices five major components.
Computer Languages
Compile: source \ (\ Rightarrow \) target program \ (\ Rightarrow \) executable program
explained: source \ (\ Rightarrow \) executable program
The first scientific computing for high-level languages : FORTRAN
C / C ++, Pascal / Object Pascal (Delphi), etc. are compiled language
interpreted language such as Java, JavaScript, VBScript, Perl, Python, Ruby, MATLAB , and so on.
Object-oriented language : discrete event simulation began in the 20th century, the language of the 1960s SIMULA67, the introduction of essentials and class inheritance, Smalltalk 20 formed in the 1970s
Hexadecimal conversion
Decimal point: for example, \ (2 ^ {--1} 2 ^ {- 2} ... \)
Computer Security
Several characteristics of the virus?
Information encoded representation
Internal code: computer to see
the outer code: posters
Character Code exchange (inner):
glyph code stored:
Chinese character coding
Area code: ASCII code of 94 characters based composition by any two of a character code ASCII code (i.e., a character consists of two bytes), the first byte is called "area", the second byte called "bit." Area code and the area code of the code bits are 01 to 94 in decimal.
GB code (GB2312-80): respectively in the area code "area" and "site" are each plus decimal 32 (hexadecimal 20H), expressed in hexadecimal. In GB code, the actual collection of characters 6763, 3755 wherein a Chinese character, alphabetical order; two characters 3008.
Machine code: the national standard code based on the area code and then each bit code plus 80H. In this case, when the characters inside the computer memory, each byte of the most significant bit is 1 , it can be distinguished from the ASCII code.
Outer code: outer code is also called the input code, the input encoding method, is used to input characters to a set of symbols in the computer keyboard, as an input kanji code. The most commonly used external code into the following categories:
- Digital code, such as the area code;
- Phonetic coding, such as spelling, Larry, NATURAL codes;
- Glyph code, such as stroke, code, Zheng codes.
Glyph code: In order to output characters on a display or a printer, the characters designed by graphic symbols bitmap , to give the corresponding lattice code (glyph code).
The original code, anti-code complement
Original code
The most significant bit is the sign bit, 0 positive, 1 negative
Inverted
N = number of the original code, in addition to the original code = negative sign bit inversion
Complement
= = Trans positive original code symbols, the inverted negative +1 =
0111 1111 .... \ (+ \ infty \)
1000 .... 0000 is \ - (\ infty \)
the two together is \ ( 1 (1111 ... 1111) \) (positive infinity infinity smaller absolute value than the negative one)
plus infinity \ (= 1 + \) minus infinity
complement arithmetic: take the sign bit is directly applied, since complement is to be added directly, and can represent negative numbers, and the full use of all bits designed, end to end to form a circular
Complement integer representation, the following statement is correct ().
The correct answer: AC Your answer: D (Error)
A bit encoding only the most negative integer of 1
B post-digit code in the determination of the absolute values can be represented by the same minimum and maximum integer integer
C is only a single integer 0 encoding
when numbers together, at the highest level if a carry, then the arithmetic overflow D with two's complement representation of
D: negative sum only certainty, the one who spilled directly to rounding
The internet
LAN (Local Area Network, LAN) , the main features: private services, small distribution, structure simple / easy cabling, network speed, low error rate
MAN (Metropolitan Area Network, MAN) , the service is usually provided within 10 to 100 km, it is generally used to provide public services, such as urban banking system, city fire system, city postal system, the city cable television / radio networks
WAN (Wide Area the Network, the WAN) , basic characteristics: wide coverage, high cost to build, and the type of complex network structure, a low transmission rate, error rate
Seven ...
IP addresses
See the previous network number, 8-bit, 128 bit is the highest
so in class A network number range: 0.0.0.0 --- 127.0.0.0 address range 0.0.0.0 to 127.255.255.255
class B network number range: 128.0.0.0 --- 191.255.0.0. Address range 128.0.0.0 to 191.255.255.255.
Class C network number range address: 192.0.0.0 --- 223.255.255.0. Address range 192.0.0.0 to 223.255.255.255
Class D address range: 239.255.255.255 224.0.0.0 ---
E class address range: 240.0.0.0 --- 247.255.255.255
6. With regard to computer networks, which the following statement is correct:
A) The reason why there are many layers of network protocols is mainly due to new technologies need to be compatible in the past the old implementation.
B) IPv6 next-generation Internet standard used to upgrade and supplement IPv5 standards.
C) TCP / IP Internet protocol suite basis, with TCP and IP and the protocol of the transport layer.
D) Each network hosts on the Internet typically requires a unique IP address, otherwise it must register a fixed domain name to indicate its address.
The answer: C; D item is no "or else"
9, the following addresses, belonging to class B IP addresses are ().
A, 27.33.119.2 B, 192.97.32.121 C, 133.201.189.32 D, 126.33.82.107
P, NP, NPC, NPhard
P class of problems: If a question can be found in a polynomial time to solve its algorithm, then the problem is the P problem.
Class NP problem: Note: NP problem is not the non-P class problems, but in polynomial time verification problem solution. Or, we can be understood as a solution to guess the problem in polynomial time.
NPC kind of problem: is defined as follows: If a problem is NP-hard problem, and all NP problems can Reductions to it. Then it is NPC class of problems. Again introduce the definition of the reduced: if a problem can be reduced to about A problem B, meaning that this issue A solution can be used to solve the problem B.
https://blog.csdn.net/qq_29176963/article/details/82776543
Memorabilia, current events
June 8, 2014, a computer (computer Eugene Gus Terman not super computer, not the computer, but a bot, is a computer program) success for humanity to believe that it is a 13-year-old boy , becoming the first computer == == ever pass the Turing test. This is considered a milestone in the development of artificial intelligence.
== == The first scientific computing for the high-level languages : FORTRAN (John Warner Backus (1977): The leading a high-level programming language first developed Fortan)
== The first object-oriented programming language == simula 67 languages
== the world's first general-purpose computer ==: ENIAC (Electronic Numerical Integrator and Computer, "Eni Akbar"), in 1946 Nian 2 Yue 14 birth at the University of Pennsylvania. Covers an area of 170 square meters, the quality of 30 tons, 5,000 times per second adder. Electronic Numerical Integrator and Computer, decimal .
== == a first computer-based (i.e., a computer program stored) von Neumann architecture: EDSAC (automatic electronic delay storage computer), a first stored program computer. 1949 years of operation.
NEW == == 1984
The first International Olympiad in Informatics == IOI == Bradley Horowitz held in Bulgaria in 1989.
In 1995 the first session == NOIP ==
1999 == NOI network synchronization season ==
China is one of the founding members of IOI. == IOI2000 == hosted by China
2007 == == CELERY
In order to strengthen the credibility of the results of the competition, since 2011, by a group try to improve the semi-finals two test instead, divided by two days. Competition questions daily from the original title == 4 to 3 questions. ==
2018 and formerly known as the International Olympiad in Informatics Chinese team trials (referred == CTSC ==). Since 2019, it changed its name to International Olympiad in Informatics China Team Selection (referred == CTS ==).
18, the following figure does not correspond to their contribution is ().
A. • Alan Turing - the manufacture of human history, the first computer ENIAC
B. • Von Neumann - "stored program 'concept and principle of the binary
C. Yao - establish the theoretical basis of quantum computer
D. Wang Xuan - Chinese character laser typesetting system
Answer: A
trial clear meaning of the questions, A is clearly wrong
Entry requirements
Beginning in 2005, NOIP no longer supports Basic; from 2022 began, is no longer supported Pascal.
When players enter the examination room, only allowed to carry pens, rubber and other non-electronic stationery admission. Allowed to bring any electronic equipment or admission, no deposit
except the storage function of the watch; phone (off), U disk or removable hard disk, keyboard, mouse, alarm clock, calculator, books, writing paper and other items must be stored in a backpack outside the examination room.
CSP-S / J: non-professional level software authentication capabilities, two levels for, respectively, CSP-J (the ⻔ level, Junior), and CSP-S (level increase, Senior), involve algorithms and programming. CSP-J and CSP-S are held respectively two: CSP-J1, CSP-S1 and CSP-J2, CSP-S2. Participate CSP-J / S of the second round, the first round must reach a certain score by only the second round. No age, gender limit
system, students and service personnel can participate.
After CSP-S / J 15 minutes of authentication, the authentication can not re-enter the point of authentication. If only allowed to leave after certification to leave ahead of the point of authentication, unless health reasons, certification shall be carried out in two hours. During the first round of certification, no person shall carry out the examination papers. When the authenticator enter the examination room, invigilators check the authenticator belongings. The authenticator can only carry pens, rubber and other non-electronic stationery admission. Allowed to bring any electronic equipment or admission, except no storage function of a watch ; phone (off), U disk or removable hard disk, keyboard, mouse, alarm clock, calculator, books, writing paper and backpacks and other items must be stored in the examination room outer. If violations brought in, once discovered, CSP-J / S certification overall responsibility for direct removal from the program's compliance certification.
During certification, such as the event of a system crash, crash or hardware failure, the authentication are required to immediately raised their hands to the examiner for help; as set by the examiner to confirm non-certified technician's liability, the authenticator when available plus compensation.
The wrong questions
Computer Basics
10 , a control can not be terminated by its own cycle known as the "death cycle", for example, in the C language program, the statement "the while (1) printf (" ");" that is, an infinite loop, it will run endlessly print number. The following statement on the death cycle, only (A) is correct.
A, does not exist an algorithm to any program and corresponding input data, you can determine whether there will be an infinite loop, therefore, any compiler systems do not do an infinite loop test.
B, some compilers system can detect an infinite loop.
C, belong to an infinite loop syntax error, since the compiler system can check a variety of grammatical errors, of course, should be able to check out an endless loop.
D, "Deadlock" cycle of death and multiple processes that appear similar, but the deadlock can be detected, and thus, the cycle of death can be detected.