第1讲
1.1 COMPUTER HARDWARE
We build computer to solve problems. Early computer solved mathematical and engineering problems, and later computers emphasized information processing for business applications. Today, computers also control machines as diverse as automobile engines, robots, and microwave ovens. A computer system solves a problem from any of these domains by accepting input, processing it, and producing output. Fig. 1-1 illustrates the function of a computer system.
Fig. 1-1 The three activities of a computer system.
Computer systems consist of hardware and software. Hardware is the physical part of the system. Once designed, hardware is difficult and expensive to change. Software is the set of programs that instruct the hardware and is easier to modify than hardware. Computers are valuable because they are general-purpose machines that can solve many different kinds of problems, as opposed to special-purpose machines that can each solve only one kind of problem. Different problems can be solved with the same hardware by supplying the system with a different set of instructions, that is, with different software.
Every computer has four basic hardware components:
l Input devices.
l Output devices.
l Main memory.
l Central processing unit(CPU).
Fig. 1-2 shows these components in a block diagram. The lines between the blocks represent the flow of information flows from one component to another on the bus, which is simply a group of wires connecting the components. Processing occurs in the CPU and main memory. The organization in Fig. 1-2, with the components connected to each other by the bus, is common.. However, other configurations are possible as well.
Computer hardware is often classified by its relative physical size:
l Small microcomputer;
l Medium minicomputer;
l Large mainframe.
Just the CPU of a mainframe often occupies an entire cabinet. Its input/output(I/O) devices and memory might fill an entire room. Microcomputers can be small enough to fit on a desk or in a briefcase. As technology advances, the amount of processing previously possible only on large machines becomes possible on smaller machines. Microcomputers now can do much of the work that only minicomputers or mainframes could do in the past.
The classification just described s based on physical size as opposed to storage size. A computer system user is generally more concerned with storage size, because that is a more direct indication of the amount of useful work that the hardware can perform. Speed of computation is another characteristic that is important to the user. Generally speaking, users want a fast CPU and large amounts of storage, but a physically small machine for the I/O devices and main memory.
When computer scientists study problems, therefore, they are concerned with space and time-the space necessary inside a computer system to store a problem and the time required to solve it. They commonly use the metric prefixes of Table 1-1 to express large or small quantities of space or time.
Table 1-1 Prefixes for powers of 10
|
Multiple
|
Prefix
|
Abbrev
|
|
109
|
giga-
|
G
|
|
106
|
mega-
|
M
|
|
103
|
kilo-
|
K
|
|
10-3
|
milli-
|
m
|
|
10-6
|
micro-
|
µ
|
|
10-9
|
nano-
|
n
|
Example Suppose it takes 4.5 microseconds, also written 4.5 µs, to transfer some information across the bus from one component to another. (a) How many seconds are required for the transfer? (b) How many transfers can take place during one minute?
(a) A time of 4.5 µs is 4.5x10-6 from Table 1-1 or 0.000 004 5 s. (b) Because ther are 60 seconds in one minute, the number of times the transfer can occur is (60 s) / (0.000 004 5 s / transfer) or 13 300 000 transfers. Note that since the original value was given with two significant figures, the result should not be given to more than two or three significant figures.
Table 1-1 shows that in the metric system the prefix kilo- is 1 000 and mega- is 1 000 000. But in computer science, a kilo- is 210 or 1024. The different between 1 000 and 1 024 is less than 3%, so you can think of a computer science kilo- as being about 1 000 even thought it is a little more. The same applies to mega- and giga- , as in Table 1-2. This time, the approximation is a little worse, but for mega- it is still within 5%.
Table 1-2 Computer science values of the large prefixes
|
Prefix
|
Computer science value
|
|
giga-
|
230 =1 073 741 824
|
|
mega-
|
220 =1 048 576
|
|
kilo-
|
210 =1 024
|
EXERCISES
1. Fill in the blank with appropriate words or phrases found behind this exercise.(P4-2)
(1) A computer system solves a problem by _____.
(2) The amount of effective work of a computer can be indicated by ____ directly.
(3) Computer systems consist of ____.
(4) Computer that can solve only one kind of problem is a ____.
(5) Computer that can solve many different kinds of problems is a ___.
(6) ____ instruct the hardware.
(7) ____ is difficult and expensive to change.
(8) We usually show the computer components in a ____.
a) general-purpose machine
b) hardware
c) accepting input, processing, and producing output
d) block diagram
e) software
f) storage size
g) special-purpose machine
h) hardware and software
2. Translate the following sentences into Chinese.(P29)
1) Absolute address: An address in a computer language that identifies a storage location or a device without the use of any intermediate reference.
2) Accumulator: The name of the CPU register in a single-address instruction format. The accumulator, or AC, is implicitly one of the two operands for the instruction.
3) Address Space: The range of addresses (memory, I/O) that can be referenced.
第2讲
1.3 WHAT IS A PROCESSOR
A processor is a functional unit that interprets and carries out instructions. Every processor comes with a unique set of operations such as ADD, STORE, or LOAD that represent the processor’s instruction set. Computer designers are fond of calling their computers machines, so the instruction set is sometimes referred to as machine instructions and the binary language in which they are written is called machine language! You shouldn’t confuse the processor’s instruction set with the instructions found in high-level programming languages, such as BASIC or Pascal.
An instruction is made up of operations that specify the function to be performed and operands that represent the data to be operated on. For example, if an instruction is to perform the operation of adding two numbers, it must know (1) what the two numbers are and (2) where the two numbers are. When the numbers are stored in the computer’s memory, they have their addresses to indicate where they are. So if an operand refers to data in the computer’s memory it is called an address. The processor’s job is to retrieve instructions and operands from memory and to perform each operation. Having done that, it signals memory to send it the next instruction.
This step-by-step operation is repeated over and over again at awesome speed. A timer called a clock releases precisely timed electrical signals that provide a regular pulse for the processor’s work. The term that is used to measure the computer’s speed is borrowed from the domain of electrical engineering and is called a megahertz (MHz), which means million cycles per second. For example, in an 8-MHz processor, the computer’s clock ticks 8 million times to every 1 second tick of an ordinary clock.
A processor is composed of two functional units – a control unit and an arithmetic/logic unit – and a set of special workspaces called registers.
1. The Control Unit
The control unit is the functional unit that is responsible for supervising the operation of the entire computer system. In some ways, it is analogous to a telephone switch-board with intelligence because it makes the connections between various functional units of the computer system and calls into operation each unit that is required by the program currently in operation.
The control unit fetches instructions from memory and determines their types or decodes them. It then breaks each instruction into a series of simple small steps or actions. By doing this, it controls the step-by-step operation of the entire computer system.
2. The Arithmetic and Logic Unit
The arithmetic and logic unit (ALU) is the functional unit that provides the computer with logical and computational capabilities. Data are brought into the ALU by the control unit, and the ALU performs whatever arithmetic or logic operations are required to help carry out the instruction.
Arithmetic operations include adding, subtracting, multiplying, and dividing. Logic operations make a comparison and take action based on the results. For example, two numbers might be compared to determine if they are equal. If they are equal, processing will continues; if they are not equal, processing will stop.
3. Registers
A register is a storage location inside the processor. Registers in the control unit are used to keep track of the overall status of the program that is running. Control unit registers store information such as the current instruction, the location of the next instruction to be executed, and the operands of the instruction. In the ALU, registers store data items that are add, subtracted, multiplied, divided, and compared. Other registers store the results of arithmetic and logic operations.
An important factor that affects the speed and performance of a processor is the size of the registers. Technically, the term word size (also called word length) describes the size of an operand register, but it is also used more loosely to describe the size of the pathways to and from the processor. Currently, word sizes in general purpose computers range from 8 to 64 bits. If the operand registers of a processor are 16 bits wide, the processor is said to be a 16-bit processor.
EXERCISES
Translate the following sentences into Chinese.(P29)
1) Direct Memory Access (DMA): A form of I/O in which a special module, called a DMA module, controls the exchange of data between main memory and an I/O module. The CPU sends a request for the transfer of a block of data to the DMA module and is interrupted only after the entire block has been transferred.
2) Indexing: A technique of address modification by means of index register.
3) Interrupt: a suspension of a process, such as the execution of a computer program, caused by an event external to that process, and performed in such a way that the process can be resumed. Synonymous with interruption.
4) Microinstruction: An instruction that controls data flow and sequencing in a processor at a more fundamental level than machine instructions. Individual machine instructions and perhaps other functions may be implemented by microprograms.
=====
第3讲
4.2 TYPICAL DATA STRUCTURES—
STACKS AND QUEUES
STACKS AND QUEUES
The data types arrays and records are native to many programming languages. By using the pointer data type and dynamic memory allocation, many programming languages also provide the facilities for constructing linked structures. Arrays, records, and linked structures provide the building blocks for implementing what we might call higher-level abstractions. The first two higher-level abstract data types that we take up – stacks and queues – are extremely important to computing.
A stack is a data type whose major attributes are determined by the rules governing the insertion and deletion of its elements. The only element that can be deleted or removed is the one that was inserted most recently. Such a structure is said to have a “last in, first out” (LIFO) behavior, or protocol.
The simplicity of the data type stack belies its importance. Many computer systems have stacks built into their circuitry and have machine-level instructions to operate the hardware stack. The sequencing of calls to and returns from subroutines follows a stack protocol. Arithmetic expressions are often evaluated by a sequence of operations on a stack. Many handheld calculators use a stack mode of operation. In studying computer science, you can expect to see many examples of tacks.
Queues occur frequently in everyday life and are therefore familiar to us.
The line of people waiting for service at a bank or for tickets at a movie theater and the line of autos at a traffic light are examples of queues. The main feature of queues is that they follow a “first come, first served” rule. Contrary to a stack, in which the latest element inserted is the first removed or served, in queues the earliest element inserted is the first served. In social settings, the rule appeals to our sense of equality and fairness.
There are many applications of the FIFO protocol of queues in computing. For example, the line of input/output (I/O) requests waiting for access to a disk drive in a multiuser time-sharing system might be a queue. The line of computing jobs waiting to be run on a computer system might also be a queue. The jobs and I/O requests are serviced in order of their arrival, that is, the first in is the first out.
There is a second kind of queue that is important. An everyday example can be seen in an emergency room of a hospital. In large emergencies it is common to first treat the worst injured patients who are likely to survive. In certain societies in which less emphasis is placed on equality, people with higher social standing may be treated first.
In computer systems, events that demand the attention of the computer are often handled according to a “most-important-event served-first”, or “highest-priority in/first-out” (HPIFO), rule. Such queues are called priority queues, in this type of queue service is not in order of time of arrival but rather in order of some measure of priority.
EXERCISES
Translate the following sentences into Chinese.(P71)
1) Data: An extremely important conception in information processing and storage. In the strictest sense, data is a representation of information, within computer systems, data is normally stored in binary format.
2) Data Item: The smallest unit of physical data for which a programmer specifies attributes.
3) String: A group of bits, or characters recognized and processed as a single unit of data.
4) Data Set: (1)A collection of data, such as an array or table of data items, a file, a program or any other organized unit of data stored or processed by a computer system. (2) A device that permits the transmission of data over a communications channel.
5) List: A data structure in which each data item can contain pointers that connect in to other data item. An ordered list of anything is a specific format. A one-dimension array of table in a program is sometimes called a list.
第4讲
Ch5-1 SUMMARY OF OPERATING SYSTEM
Operating systems have developed over the past thirty years for two main purposes. First, they provide a convenient environment for the development and execution of programs. Second, operating systems attempt to schedule computational activities to ensure good performance of the computing system.
As we have stated, operating systems are normally unique to their manufacturers and the hardware in which they are run. Generally, when a new computer system is installed, operational software suitable to that hardware is purchased. Users want reliable operational software that can effectively support their processing activities.
Though operational software varies with manufacturers, it has similar characteristics. Modern hardware, because of its sophistication, requires that operating systems meet certain specific standards. For example, considering the present state of the field, an operating system must support some form of online processing. Functions normally associated with operational software are:
(1) Job management;
(2) Resource management;
(3) Control of I/O operations;
(4) Error recovery;
(5) Memory management.
1. Job Management
A very important responsibility of any operational software is the scheduling of jobs to be handled by a computer system. This is one of the main tasks of the job management function. The operating system sets up the order in which programs are processed, and defines the sequence in which particular jobs are executed. The term “job queue” is often used to describe the series of jobs awaiting execution. The operating system weighs a variety of factors in creating the job queue. These include which jobs are currently being processed, the system’s resources being used, which resources will be needed to handle upcoming programs, the priority of the job compared to other tasks, and any special processing requirements to which the system must respond.
The operational software must be able to assess these factors and control the order in which jobs are processed.
Batch systems allowed automatic job sequencing by a resident monitor and improved the overall utilization of the computer greatly. The computer no longer had to wait for human operation. CPU utilization was still low, however, because of the slow speed of the I/O devices relative to the CPU. Offline operation of slow devices was tried. Buffering was another approach to improving system performance by overlapping the input, output, and computation of a single job. Finally, spooling allowed the CPU to overlap the input of one job with the computation and output of other jobs.
Spooling also provides a pool of jobs which have been read and are waiting to be run. This job pool supports the concept of multiprogramming. With multiprogramming, several jobs are kept in memory at one time; the CPU is switched back and forth between them in order to increase CPU utilization and to decrease the total real time needed to execute a job.
Multiprogramming, which was developed to improve performance, also allows time sharing. Time-shared operating systems allow many users (from one to several hundred) to use a computer system interleavingly at the same time. Other operating systems type include real-time systems and multiprocessor systems.
2. Resource Management
the management of resources in a computer system is another major concern of the operating system. Obviously, a program cannot use a device if that hardware is unavailable. As we have seen, the operational software oversees the execution of all programs. It also monitors the devices being used. To accomplish this, it establishes a table in which programs are matched against the devices they are using or will use. The operating system checks this table to approve or deny use of a specific device.
3. Control of I/O Operations
Allocation of a system’s resources is closely tied to the operational software’s control of I/O operations. As access is often necessary to a particular device before I/O operations may begin, the operating system must coordinate I/O operations and the devices on which they are performed. In effect, it sets up a directory of programs undergoing execution and the devices they must use in completing I/O operations. Using control statements, jobs may call for specific devices. This lets users read data from specific sites or print information at selected offices. Taking advantage of this facility, data read from one location may be distributed throughout computerized system.
To facilitate execution of I/O operations, most operating systems have standard set of control instructions to handle the processing of all input and output instructions. These standard instructions, referred to as the input/output control system (IOCS), are an integral part of most operating system. They simplify the means by which all programs being processed may undertake I/O operations.
In effect, the program undergoing execution signals the operating system that an I/O operation is desired, using a specific I/O device. The controlling software calls on the IOCS software to actually complete the I/O operation. Considering the level of I/O activity in most programs, the IOCS instructions are extremely vital.
EXERCISES
Translate the following sentences into Chinese.(P86)
1) Error Recovery: The activities undertaken by the operating system to restore processing when errors are found.
2) Kernel: The core portion of an operating system responsible for managing system resources.
3) Multiprocessing: A computer system that uses two or more processors that share memory and input and output devices.
4) Thread: A concurrent process that is actually part of a large process or program. Multitasking operating systems allow single program to contain several threads that all run at the same time.
5) Virtual Storage (VS): A software technique that redistributes the CPU’s resource by dividing large programs into workable units called pages.
第5讲
Ch6.2 PROGRAMMING LANGUAGE
A language is a system of communication. A programming language consists of all the symbols, characters, and usage rules that permit people to communicate with computers. Some programming languages are created to serve a special purpose (e.g., controlling a robot), while others are more flexible general-purpose tools that are suitable for many types of applications. However, every programming language must accept certain types of written instructions that will enable a computer system to perform a number of familiar operations. That is, every language must have instructions that fall into the following familiar categories:
(1) Input/output instructions. Required to permit communication between I/O devices and the central processor, these instructions provide details on the type of input or output operation to be performed and the storage locations to be used during the operation.
(2) Calculation instructions. Instructions to permit addition, subtraction, multiplication, and division during processing are, of course, common in all programming languages.
(3) Logic/comparison instruction. These instructions are used to transfer program control, and are needed in the selection and loop structures that are followed to prepare programs. During processing, two data items may be compared as a result of the execution of logic instruction. As you know, program control can follow different paths depending on the outcome of a selection test (IF R>0 THEN A, ELSE B). And a loop can be continued or terminated depending on the outcome of an exit condition test (does Q=-99.9?). In addition to the instructions in languages that set up tests or comparisons to effect the transfer of program control, there are also unconditional transfer instructions available that are not based on the outcome of comparisons.
(4) Storage/retrieval and movement instructions. These instructions are used to store, retrieve, and move data during processing. Data may be copied from one storage location to another and retrieved as needed.
But even though all programming languages have an instruction set that permits these familiar operations to be performed, there’s marked difference to be found in the symbols, characters, and syntax of machine languages, assembly languages, and high-level languages.
1. Machine Languages
A computer’s machine language consists of strings of binary numbers and is the only one the CPU directly “understands”. An instruction prepared in any machine language will have at least two parts. The first part is the command or operation, and it tells the computer what function to perform. Every computer has an operation code or “op code” for each of its functions. The second part of the instruction is the operand, and it tells the computer where to find or store the data or other instructions that are to be manipulated. The number of operands in an instruction varies among computers. In a single-operand machine, the binary equivalent of “ADD 0184” could cause the value in address 0184 to be added to the value stored in a register in the arithmetic-logic unit. In a two-operand machine, the binary representation for “ADD 0184 8672” could cause the value in address 8672 to be added to the number in location 0184. The single-operand format is popular in the smallest microcomputers; the two-operand structure is likely to be available in most other machines.
By today’s standards, early computers were intolerant. Programmers had to translate instructions directly into the machine-language form that computers understood. For example, the programmer writing the instruction to “ADD 0184” for an early IBM machine would have written:
000100000000000000000010111000
In addition to remembering the dozens of code numbers for the commands in the machine’s instruction set, a programmer was also forced to keep track of the storage locations of data and instructions. The initial coding often took months, was therefore quite expensive, and often resulted in error. Checking instructions to locate errors was about as tedious as writing them initially. And if a program had to be modified at a later date, the work involved could take weeks to finish.
2. Assembly Languages
To ease the programmer’s burden, mnemonic operation codes and symbolic addresses were developed in the early 1950s. One of the first steps in improving the program preparation process was to substitute letter symbols – mnemonics – for the numeric machine – language operation codes. Each computer now has a mnemonic code, although, of course, the actual symbols vary among makes and models. Machine language is still used by the computer as it processes data, but assembly language software first translates the specified operation code symbol into its machine-language equivalent.
And this improvement sets the stage for further advances. If the computer could translate convenient symbols into basic operations, why couldn’t it also perform other clerical coding functions, such as assigning storage addresses to data? Symbolic addressing is the practice of expressing an address not in terms of its absolute numerical location, but rather in terms of symbols convenient to the programmer.
In the early stages of symbolic addressing, the programmer assigned a symbolic name and an actual address to a data item. For example, the total value of merchandise purchased during a month by a department store customer might be assigned to address 0063 by the programmer and given the symbolic name TOTAL. The value of merchandise returned unused during the month might be assigned to address 2047 and given the symbolic name CREDIT. Then, for the remainder of the program, the programmer would refer to the symbolic names rather than to the addresses when such items were to be processed. Thus, an instruction might be written “S CREDIT, TOTAL” to subtract the value of returned goods from the total amount purchased. The assembly language software might then translate the symbolic instruction into this machine-language string of bits:
011111 011111111111 000000111111
Mnemonic op code 2047 0063
(s) (CREDIT) (TOTAL)
Another improvement followed. The programmer turned the task of assigning and keeping track of instruction addresses over to the computer. The programmer merely told the machine the storage address number of the first program instruction, and the assembly language software then automatically stored all others in sequence from that point. So if another instruction was added to the program later, it was not necessary to modify the addresses of all instructions that followed the point of insertion (as would have to be done in the case of programs written in machine language). Instead, the processor automatically adjusted storage locations the next time the program ran.
Programmers no longer assign actual address numbers to symbolic data items as they did earlier. Now they merely specify where they want the first location in the program to be, and an assembly language program takes it from there, allocating locations for instructions and data.
This assembly program, or assembler, also enables the computer to convert the programmer’s assembly language instructions into its own machine code. A program of instructions written by a programmer in an assembly language is called a source program. After this source program has been converted into machine code by an assembler, it’s referred to as an object program.
Assembly languages have advantages over machine languages. They save time and reduce detail. Fewer errors are made, and those that are made are easier to find. And assembly programs are easier for people to modify than machine-language programs. But there are limitations. Coding in assembly language is still time consuming. And a big drawback of assembly languages is that they are machine-oriented. That is, they are designed for the specific make and model of processor being used. Programs might have to be recoded for a different machine.
3. High-Level Languages
The earlier assembly programs produced only one machine instruction for each source program instruction. To speed up coding, assembly programs were developed that could produce a variable amount of machine-language code for each source program instruction. In other words, a single macroinstruction might produce several lines of machine-language code. For example, the programmer might write “READ FILE,” and the translating software might then automatically provide a detailed series of previously prepared machine-language instructions which would copy a record into primary storage from the file of data being read by the input device. Thus, the programmer was relieved of the task of writing an instruction for every machine operation performed.
The development of mnemonic techniques and macroinstructions led, in turn, to the development of high-level languages that are often oriented toward a particular class of processing problems. For example, a number of languages have been designed to process problems of a scientific-mathematic nature, and other languages have appeared that emphasize file processing applications.
Unlike assembly programs, high-level language programs may be used with different makes of computers with little modification. Thus, reprogramming expense may be greatly reduced when new equipment is acquired. Other advantages of high-level languages are:
l They are easier to learn than assembly languages.
l They require less time to write.
l They provide better documentation.
l They are easier to maintain.
l A programmer skilled in writing programs in such a language is not restricted to using a single type of machine.
EXERCISES
Translate the following sentences into Chinese.(P107)
1) Special-purpose program: Programs that are dedicated to performing single-user tasks, for example, medical billing or patient tracking.
2) Problem-oriented language: Any programming designed to solve a specific type of problem.
3) Binding: The match between a message received by an object and one of its methods. Can be done static, that is, at compile-time, or dynamic, that is, at run-time.
4) Class: A class that describes a group of similar objects. Elements of such a group called instances. The class describes variable/member fields and methods/member functions that are common to all instances of the class.
5) Derived class: A class that inherits features from a base class. It is a subclass of the base class.
6) Feature: Collective term for variable/field or method/function of a class. A feature of a class can be an instance variable or a method.
第6讲
Ch7.2 SQL AND SQL SERVER
IBM Invented a computer language back In the 1970s designed specifically for database quires called SEQUEL; those letters stand for Structured English Query Language. Over time, the language has been added to so that It Is not just a language for queries, but can also build database and manage the database engine’s security. Because of this heritage you can pronounce It “sequel” or spell It out “S-Q-L.” There are various versions of SQL sued In today’s database engines. Microsoft SQL Server uses a version called Transact-SQL, or T-SQL, which stands for Transaction SQL.
1. What Is SQL Server?
SQL Server Is a client/server relational database management system (RDBMS) that uses Transact-SQL to send requests between a client and SQL Server.
2. Client/Server Architecture
The terms client, server, and client/server can be used to refer to very general concepts or to specific items of hardware or software. At the most general level, a client is any component of a system that requests services or resources from other components of a system. A server is any component of a system that provides services or resources to other components of a system.
For example, when you print a document from your workstation on a network, the workstation is the client and the machine that does the print spooling is the server.
Any client/server data-based system consists of the following components:
l The server – A collection of data items and supporting objects organized and presented to facilitate services, such as searching, sorting, recombining, retrieving, updating, and analyzing data. The database consists of the physical storage of data and the database services. All data access occurs through the server; the physical data is never accessed directly by the client.
l The client – A software program that might be used Interactively by a person or that could be an automated process. This includes all software that interacts with the server, either requesting data from or sending data to the database. Examples are management utilities (those that are part of the SQL Server product as well as those bought separately), ad hoc query and reporting software, custom applications, off-the-shelf applications, and Web server-based applications.
l The communication between the client and the server – The communication between the client and the server depends largely on how the client and server are implemented. Both physical and logical layers of communication can be identified.
When you communicate with someone using the telephone, the telephone system is the physical layer and a spoken natural language is the logical layer of communication. For a data-based system, the physical layer can be a network If the server and the client are on different computers. It can be interprocess communication If the server and the client are on the same computer. The logical communication structure of the physical layer may be low-level operating system calls, a proprietary data access language, or the open structured query language (SQL).
3. SQL Server Platforms
SQL Server runs on the operating system shown In Fig. 7-4. The SQL Server version 7 server software runs only on the Windows 32-bit API-based operating systems, but you can use all of the operating system platforms to create and execute client applications.
Fig. 7-4 Operating systems on which the SQL Server client and server software can run
The following Table 7-1 gives more detail about operating systems and how they do or do not support SQL Server 7.
Table 7-1 Operating system supporting SQL Server 7
|
Platform
|
Server software
|
Client software
|
|
Microsoft Windows 95 or later
|
Yes; runs as an application
|
Yes
|
|
Microsoft Windows NT Workstation 4.0 or later
|
Yes; runs as a service
|
Yes
|
|
Windows NT Server
|
Yes; runs as a service
|
Yes
|
|
Windows NT Server Enterprise Edition
|
Yes; runs as a service
|
Yes
|
EXERCISES
Translate the following sentences into Chinese.(P122-123)
1) Application program: (1) A computer program that provides features and functions particular to the user’s information needs; (2) One of the components of a database application that provides such features and functions.
2) Associative entities: Abstract entities storing data from a relationship between two main concepts.
3) Associative table: A table holding data pertaining to associative entities.
4) Client/server architecture: A local area network in which specially designated microcomputers called servers provide specialized service on behalf of the users’ computers, which are called clients. Often used for database applications in which the database is processed by a DBMS located on the database server computer; application programs on client computers call on the DBMS on the database server for database processing.
5) Deadlock: A condition that occurs when two users invoke conflicting locks. User A is waiting for a record that user B has locked, while user B is waiting for a record that user A has locked.
6) Server platform: Integration of the server machine, its operating system, and its communications environment.
7) Middleware: Communications-oriented software between client and server.
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