第2章 Hardware Knowledge
2.1 Computer Hardware Basics
2.2 CPU
2.3 Memory
2.4 Input / Output Devices
2.5 Parallel Organization
2.1 Computer Hardware Basics
? Flip-Flop and Clock
? Shift registers
? Combinational Circuit
? Logic Systems
? Logic Circuits
Flip-Flop and Clock
? Microprocessors employ both latches and flip-flops.
? A flip-flop is a synchronous device; it is clocked, and it can change state on
? Clock pulses are basically square waves; they may have a very low repetition, or they may have a very high repetition rate.
RS flip-flop
Shift registers
? A register capable of shifting its binary information in on
? All flip-flops receive common clock pulses that initiate the shift from on
? A register capable of shifting in on
? Some shift registers provide the necessary input terminals for parallel transfer.
4-bit shift register
The capabilities of register
? An input for clock pulses to synchronize all operations.
? A shift-right operation and a serial input line associated with the shift-right.
? A shift-left operation and a serial input line associated with the shift-left.
? A parallel load operation and n input lines associated with the parallel transfer.
? N parallel output lines.
? A control state that leaves the information in the register unchanged even though clock pulses are applied continuously.
Combinational Circuit
? A combinational circuit is a connected arrangement of logic gates with a set of inputs and outputs. At any given time, the binary values of the outputs are a function of the binary combination of the inputs.
? A combinational circuit can be described by a truth table showing the binary relationship between the n input variables and the m output variables.
Block diagram of a combinational circuit
Logic Systems
? In a DC, or level-logic, system a bit is implemented as on
? The digital levels are not specified precisely, but each state is defined by a voltage range about a designated level, such as 4V±1V and 0.2V±0.2V.
? In a dynamic, or pulse-logic, system a bit is recognized by the presence or absence of a pulse.
Logic Circuits
? The design of digital computers is based on a logical methodology called Boolean Algebra which uses three basic operations: logical addition, called the OR function; logical multiplication, called the AND function; and logical complementation, called the NOT function.
? The variables in Boolean algebra are binary, namely, the resulting variable of an operation or a set of operations can have on
Key Words
? arbitrary 任意的
? arrangement 排列，整理
? asynchronous 异步的
? bi-directional 双向的
? Boolean function 布尔函数
? cascade 级连的，串级
? combinational circuit 组合电路
? complement 补充，补足
? configuration 配置，结构
? flip-flop 触发器
? inasmuch 因……之故
? inhibit 禁止，抑制
? initiate 开始，激发
? interconnection 互联网络
? microprocessor 微处理器
? negative-logic 负逻辑
? parallel transfer 并行传送
? serial 顺序的，串行的
? significance 重要性，意义
? square-wave 方波
? unidirectional 单向的
Notes
? [1] The logical configuration of a shift register consists of a chain of flip-flops in cascade, with the output of on
? 此句中的“with the output of on
? 译文：移位寄存器的逻辑结构是由一连串串接的触发器所组成的，一个触发器的输出端连接到相邻的触发器的输入端。
? [2] Sometimes it is necessary to control the shift so that it occurs with certain clock pulses but not with others.
? 此句中的“it”是形式主语，“to control the shift”是真正主语，so that引导状语从句。
? 译文：有时候有必要对移位进行控制以便移位只对某些特定脉冲而不对其他脉冲发生。
? [3] A register that can shift in both directions is called a bi-directional shift register.
? 本句用被动语态表示客观性，“that can shift in both directions”是主语从句，修饰“a register”。
? 译文：能够在两个方向上移位的寄存器叫做双向移位寄存器。
? [4] A combinational circuit transforms binary information from the given input data to the required output data.
? 本句的介词短语“from … to …”作宾语补足语，进一步说明宾语“binary information”。
? 译文：组合电路通过传输二进制信息，使得给定的输入数据产生了所需要的输出数据。
? [5] A combinational circuit can also be specified with m Boolean functions, on
? 本句的“on
? 译文：组合电路也能规定m种布尔函数，每种函数对应一个输出变量。
词组翻译练习
? (1) 锁存器 latch
? (2) 逻辑电路 logic circuit
? (3) R-S触发器 R-S flip-flop
? (4) 有效数据 valid data
? (5) 向左移位操作 a shift-left operation
? (6) 输出变量 output variable
? (7) 8位移位寄存器 8-bit shift register
? (8) 二进制信息 binary information
Reading material：Digital Computer System
? The four basic units of simplified computer: the input unit, central processing unit, memory unit, and output unit.
? The central processing unit (CPU) is the heart of the computer system. It is responsible for performing all arithmetic operations and logic decisions initiated by the program.
? The memory unit of the computer is used to store information such as numbers, names, and addresses.
? In computer system, memory is divided into two different sections, known as main storage and auxiliary storage. They are also sometimes called internal memory and external memory respectively.
? The input and output units are the means by which the CPU communicates with the outside world.
? The input unit is used to input information and commands to the CPU for processing.
? After processing, the information that results must be output.
? This output of data from the system is performed under control of the output unit.
A Digital Computer
2.2 CPU
? The CPU means the Central Processing Unit. It is the heart of a computer system.
? A CPU can be a single microprocessor chip, a set of chips, or a box of boards of transistors, chips, wires, and connectors.
? Differences in CPUs distinguish mainframes, mini- and microcomputers.
? A processor is composed of two functional units: a control unit and an arithmetic / logic unit, and a set of special workspaces called registers.
Most computers have three basic capabilities
? Computers have circuits for performing arithmetic operations, such as: addition, subtraction, division, multiplication and exponentiation.
? Computers have a means of communicating with the user.
? Computers have circuits which can make decisions.
The control unit
? The control unit is the functional unit that is responsible for supervising the operation of the entire computer system.
? The control unit fetches instructions from memory and determines their type 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.
The Arithmetic / Logic Unit
? 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 instructions.
? Arithmetic operations include adding, subtracting, multiplying, and dividing. Logic operations make a comparison and take action based on the results.
Registers
? 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 added, subtracted, multiplied, divided, and compared.
? Other registers store the results of arithmetic and logic operations.
Instruction
? An instruction is made up of operations that specify the function to be performed and operands that represent the data to be operated on.
? 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 sequence of steps is frequently referred to as the fetch-decode-execute cycle.
Key Words
? analogous 类似的，相似的
? Arithmetic / Logic Unit 算术逻辑单元
? awesome 惊人的，令人敬畏的
? capability 性能，能力
? chip 芯片
? decode 解码，译码
? exponentiation 幂运算
? fetch 获取，取得
? instantaneously 瞬间地，即时地
? microelectronic techniques 微电子技术
? operand 操作数
? originality 创意，创造力
? overall 全部的
? register 寄存器
? remarkable 显著的，不平常的
? retrieve 恢复
? switchboard 接线总机
? transistor 晶体管
Notes
? [1] The program, which tells the computers what to do and the data, which provide the information needed to solve the problem, are kept inside the computer in a place called memory.
? 这里的主语是“the program and the data”，由which引导的两个定语从句分别修饰the program和the data。
? 译文：程序的作用是指示计算机如何工作，而数据则是为解决问题提供的所需要的信息，两者都存储在存储器里。
? [2] The Arithmetic / Logic Unit (ALU) is the functional unit that provides the computer with logical and computational capabilities.
? 本句由“that”引导定语从句，修饰“the functional unit”。
? 译文：算术逻辑单元（ALU）是为计算机提供逻辑及计算能力的功能部件。
? [3] For example, if an instruction is to perform the operation of adding two numbers, it must know what the two numbers are and where the two numbers are.
? 这里的“what the two numbers are and where the two numbers are”作宾语，它由两个并列的从句组成。
? 译文：例如，一条指令要完成两数相加的操作，它就必须知道：这两个数是什么？这两个数在哪儿？
? [4] A timer called a clock releases precisely timed electrical signals that provide a regular pulse for the processor’s work.
? 本句中的“that provide a regular pulse for the processor’s work”修饰electrical signals。
? 译文：一个称作时钟的计时器准确地发出定时电信号，该信号为处理器工作提供有规律的脉冲信号。
词组翻译练习
(1) 智能 intelligence
(2) 取指—译码—执行 fetch-decode-execute
(3) 算术逻辑运算 Arithmetic Logical Operations
(4) 硅 silicon
(5) 区别，辨别 distinguish
(6) 顺序 sequence
(7) 发出，释放 release
(8) 兆赫 Megahertz
Reading Material：Microprocessor
? Microcomputer, or micro for short, is a kind of computers. It was born in the early 1970s.
? The central processor of the micro, called the microprocessor, is built as a single semiconductor device; that is, the thousands of individual circuit elements necessary to perform all the logical and arithmetic functions of a computer are manufactured as a single chip.
2.3 Memory
? A memory cell is a circuit, or in some cases just a single device, that can store a bit of information.
? A systematic arrangement of memory cells constitutes a memory.
? Two basic types of semiconductor memory are random access memory (RAM) and read-on
RAM and ROM
? Implicit in the definition of the RAM is that both the read and the write operations are permissible in each cell with also approximately the same access time.
? The set of data in ROM is generally considered to be fixed, although in some designs the data can be altered.
? A ROM may be used, for example, to store the instructions of a system operating program.
SRAM and DRAM
? Two type of RAM are the static RAM (SRAM) and dynamic RAM (DRAM).
? A static RAM consists of a basic bi-stable flip-flop circuit that needs on
? A dynamic RAM is an MOS memory that stores on
? The advantage of the SRAM is that this circuit does not need the additional complexity of a refresh cycle and refresh circuitry, but the disadvantage is that this circuit is fairly large.
? In general, a SRAM requires six transistors.
? The advantage of a DRAM is that it consists on
The general types of ROM
? The first is programmed either by the manufacturer (mask programmable) or by the user (programmable, or PROM).
? Once the ROM has been programmed by either method, the data in the memory are fixed and cannot be altered.
? The second type of ROM may be referred to as an alterable ROM in that the data in the ROM may be reprogrammed if desired.
? This type of ROM may be called an EPROM (erasable programmable ROM), EEPROM (electrically erasable PROM), or flash memory.
Basic memory architecture
Memory addresses
? Computers that use the binary number system also express memory addresses as binary numbers.
? If an address has m bits, the maximum number of cells directly addressable is 2 m.
? The significance of the cell is that it is the smallest addressable unit. In recent years, most computer manufactures have standardized on an 8-bit cell, which is called a byte.
? Bytes are grouped into words.
The 80x86 processors
? The 80x86 processors, operating in real mode, have physical address-ability to 1 megabyte of memory.
? EMS was developed to allow real mode processing to have access to additional memory.
? It uses a technique called paging, or bank switching.
? The requirements for expanded memory include additional hardware and a software device driver.
Key Words
adjacent 邻近的，接近的
allocate 分配，分派
approximately 大约，大致，近于
consecutive 连续的，连贯的
constitute 构成，组成
erasable 可擦除的
essential 必要的，基本的
etch 蚀刻
hexadecimal 十六进制的
implicit 暗示的，绝对的
kilobyte 千字节
manipulate 操作
megabyte 兆字节
non-metallic 非金属的
octal 八进制的
property 适当地，相当地
redirect 更改地址
refer to 指，提到，参照
refresh 刷新
semiconductor 半导体
turn off 关闭
virtually 事实上
volatile 易失的
Notes
[1] The number of bits in the address is related to the maximum number of directly addressable cells in the memory and is independent of the number of bits per cell.
本句中，of directly addressable cells in the memory修饰the maximum number。
译文：地址的位数与存储器可直接寻址的最大单元数量有关，而与每个单元的位数无关。
[2] Thus a 16-bit words, whereas a 32-bit machine will have 32-bit registers and instructions for moving, adding, subtracting, and otherwise manipulating 32-bit words.
Thus a 16-bit words是一个省略句，这里的whereas作“而”讲。
译文：因而16位机器具有16位的寄存器和指令以实现16位字的操作；32位机器则有32位的寄存器和指令，以实现传送、加法、减法和其它他32位字的操作。
[3] This was the ability to etch thousands of integrated circuits on
由which引导的是非限定性定语从句，用来修饰silicon。
译文：这就是将成千上万个集成电路蚀刻在一小块硅（芯）片上的能力。硅片是具有半导体特性的非金属元件。
[4] When a program allocates expanded memory pages, the EMM returns a handle to the requesting program.
本句中，由when引导了一个时间状语从句。
译文：当一个程序装入扩展存储器页中时，EMM就将一个标志回复给这个请求程序。
词组翻译练习
(1) 扩展存储器 expanded memory
(2) 半导体存储器 semiconductor memory
(3) 外围电路 peripheral circuit
(4) 实模式 the real mode
(5) 寻址能力 address ability
(6) 组织 organization
(7) 只读存储器 Read Only Memory
(8) 随机存取存储器 Random Access Memory
Reading material :Magnetic Disks and Optical Disks
? There are two major types of magnetic disks: floppy disks and hard disks.
? Both types of disks rely on a rotating platter coated with a magnetic surface and use a moveable read/write head to access the disk.
? Every user has used hard disks and liked them very much since they have gigantic storage capacity and work fast, especially since operating systems grow larger and larger.
? An optical disk is a disk on which data are encoded for retrieval by a laser.
? Optical disks offer information densities far beyond the range of current magnetic mass-storage devices.
? Read-on
? The most popular version of read-on
? Write-on
? Erasable optical disks use lasers to read and write information to and from the disk but also use a magnetic material on the surface of the disk and a magnetic write head to achieve erasability.
2.4 Input / Output Devices
? Input is a process that involves the use of a device to encode or transform data into digital codes that the computer can process.
? Input devices enable you to input data and commands into the computer.
? In most cases, it is the job of the output device to decode these coded symbols into a form of information that is easy for people to use or understand, such as text, pictures, graphics, or sound.
Keyboard
? The keyboard is on
? It is the way you will most commonly communicate with a computer.
? The computer keyboard is much like the keyboard of a typewriter.
? The computer keyboard has some additional keys called modifier keys. These are the Shift, Ctrl (control) and Alt (alternate) keys.
Mouse
? A mouse is a small device that a computer user pushes across a desk surface in order to point to a place on a display screen and to select on
? A mouse consists of a metal or plastic housing or casing, a ball that sticks out of the bottom of the casing and rolls on a flat surface, on
? The most conventional kind of mouse has two buttons on the top: the left on
? The second button, on the right, usually provides some less-frequently needed capability.
? For example, when viewing a Web page, you can click on an image to get a pop-up mean that, among other things, lets you save the image on your hard disk.
Monitor
? Monitors maybe are on
? A character-based display divided the screen into a grid of rectangles, each of which can display a single character.
? A bitmap display divides the screen into a matrix of tiny, square “dots” called pixels. Any characters or graphics that the computer displays on the screen must be constructed of dot patterns within the screen matrix.
? Resolution refers to the number of individual dots of color, known as pixels, contained on a display.
? Dot pitch is the measure of how much space there is between a display’s pixels.
? In monitors based on CRT technology, the refresh rate is the number of times that the image on the display is drawn each second.
? The scan style of a electron gun in a tube is divided into two styles: interlace and non-interlace.
Scanner
? A scanner is a device that can read text or illustrations printed on paper and translate the information into a form the computer can use.
? A scanner works by digitizing an image, dividing it into a grid of boxes and representing each box with either a zero or a on
? Optical scanners do not distinguish text from illustrations; they represent all images as bit maps.
Key Words
alphabetic 字母的
apparently 清楚地，显然地
bit map 位图
capital letter 大写字母
cursor 光标
digitize 数字化
electron-beam 电子束
flicker 闪耀，闪烁
illustration 例证，插图
integral 整体，整数
layout 布局
manufacture 制造
matrix 矩阵，阵列
non-interlace 非隔行
pixel 像素
rectangle 矩形
replacement 更换，代替
resolution 分辨率
retinal 视网膜的
scanner 扫描仪
sensor 传感器
sophisticate 复杂
typewriter 打字机
venerable 庄严的
Notes
[1] What a computer program produces is a stream of coded symbols.
本句中的“What a computer program produces”作主语。
译文：计算机程序产生的是编码的符号流。
[2] The arrow keys allow you to move the position of the cursor on the screen.
本句中的不定式结构“to move the position of the cursor on the screen”作宾语补足语。
译文：方向键允许你移动光标在屏幕上的位置。
[3] The second button, on the right, usually provides some less-frequently needed capability.
本句的“on the right”是同位语，进一步说明主语。
译文：第二个按键在右边，提供了某些不太常用的功能。
[4] In interlace style, electron-beam sweeps elements in odd rows first time and does elements in even rows second time.
本句中的electron-beam译作电子射枪，elements译作像素。
译文：在隔行方式中，电子射枪首先扫描奇数项中的像素，第二次再扫描偶数项中的像素。
[5] To edit text read by an optical scanner, you need an optical character recognition (OCR) system to translate the image into ASCII characters.
本句的“To edit text read by an optical scanner”是目的状态，而“to translate …”是宾语补足语。
译文：要编辑由光学扫描仪读入的文本，你需要一套光学字符识别系统（OCR）将图像翻译成ASCII码。
词组翻译练习
(1) 基于字符的显示器 character-based diaplay
(2) 隔行及非隔行 interlace and non-interlace
(3) 布局 layout
(4) 输入/输出设备 input/output device
(5) 功能键 function key
(6) 光标 cursor
(7) 像素距离 element distance
(8) 分辨率 solution
Reading material :Printer
? Printers are used to produce a paper or hard copy of the processing results. There are several types of printers with tremendous differences in speed, print quality, price and special features.
? Dot-Matrix Impact Printers
? Dot-Matrix Thermal Printers
? Laser Printers
? Ink-Jet Printers
2.5 Parallel Organization
? Multiprocessing
? Organization
? Time-Shared Bus
? Multi-port Memory
? Central Control Unit
? Goals of Parallel Processing
Multiprocessing
? The use of multiple processors is motivated by considerations of performance and reliability.
? We can classify such systems as follows:
? Loosely Coupled Multiprocessing
? Functionally Specialized Processors
? Tightly Coupled Multiprocessing
? Parallel Processing
The key characteristics of a multiprocessor
? It contains two or more similar general-purpose processors of comparable capability.
? All processors share access to global (common) memory. Some local (private) memory may also be used.
? All processors share access to I/O devices, either through the same channels or through different channels that provide paths to the same devices.
? The system is controlled by an integrated operating system that provides interaction between processors and their programs that the job, task, file, and data element levels.
Organization
? A multiprocessor system has two or more CPUs in general.
? Each CPU is self-contained, including a control unit, ALU, registers, and, possibly, cache.
? Each CPU has access to a shared main memory and the I/O devices through some form of interconnection mechanism.
? The organization of a multiprocessor system can be classified as Time-Shared or Common Bus, Multi-port Memory and Central Control Unit.
Time-Shared Bus
? The time-shared bus is the simplest mechanism for constructing a multiprocessor system.
? The structure and interfaces are basically the same as for a single-processor system that uses a bus interconnection.
? The bus consists of control, address, and data lines.
The bus organization has several advantages compared to other approaches
? Simplicity: The physical interface and the addressing, arbitration, and time-sharing logic of each processor remain the same as in a single-processor system.
? Flexibility: It is generally easy to expand the system by attaching more CPUs to the bus.
? Reliability: The bus is essentially a passive medium, and the failure of any attached device should not cause failure of the whole system.
Multi-port Memory
? The multi-port memory approach allows the direct, independent access of main memory modules by each CPU and I/O module.
? The multi-port memory approach is more complex than the bus approach, requiring a fair amount of logic to be added to the memory system.
? It should, however, provide better performance since each processor has a dedicated path to each memory module.
? Another advantage of multi-port is that it is possible to configure portions of memory as “private” to on
Central Control Unit
? The central control unit is an extension of the system controller concept.
? The controller can buffer requests and perform arbitration and timing functions.
? It can also pass status and control messages between CPUs and perform cache update alerting.
Goals of Parallel Processing
? Reduce User’s Time
? Cheapest Possible Solution strategy
? Local versus Non-local Resources
? Memory Constraints
Key Words
aggregate 合计，总计
alleviate 减轻，使缓和
arbitration 仲裁，公断
autonomous 自治的
computationally 计算地
conflict 冲突，战争
constraint 强制，约束
cooperatively 合作地，协作的
dramatically 戏剧地，突然地
elaborate 详细说明
facilitate 使容易，促进
feature 特征，特色
flexibility 适应性
latency 潜伏，潜在
parallelism 并行的
proportionally 成比例地，相称地
reliability 可靠性
simplicity 简单，简朴
somewhat 某物
strategy 策略，战略
submit 提交
susceptible 易受影响的
Notes
[1] As computer technology has evolved, and as the cost of computer hardware has dropped, computer designers have sought more and more opportunities for parallelism, usually to improve performance and, in some cases, to improve reliability.
本句由“As”引导原因状语从句，“and as the cost …”是同位语，表示另一个原因，“in some cases”是插入语。
译文：随着计算机技术的发展以及计算机硬件价格的降低，计算机的设计者开始寻找越来越多并行操作的机会，通常是为了提高操作效率，以及在某些情况下提高可靠性。
[2] The memory is often organized so that multiple simultaneous accesses to separate blocks of memory are possible.
本句由“so that”引导目的状语从句。
译文：通过对内存的组织，对内存不同分块的同时操作变为可行。
[3] When on
本句由“When”引导时间状语从句，“if necessary”是插入语。
译文：当一个模块在控制总线时，其他的模块被锁定，而且在必要时要将其操作悬挂，直到总线的存取能够实现为止。
4] The multi-port memory approach is more complex than the bus approach, requiring a fair amount of logic to be added to the memory system.
本句由“more…than”实现比较，“requiring a fair…”是现在分词短语作主语补足语。
译文：多端口内存技术比总线技术要复杂，需要给内存加上相当数量的逻辑。
词组翻译练习
(1) 高速缓冲存储器 cache memory
(2) 数据流 data stream
(3) 单处理器 single-processor
(4) 多端口存储器 multi-port memory
(5) 公共数据区 common data area
(6) 松耦合多处理器 loosely coupled multiprocessing
(7) 输入/输出处理器 I/O processor
(8) 集成控制 integrated control
Reading Material：Multiprocessing
? A system in which each processor has a private (local) main memory and shares secondary (global) memory with the others is a secondary memory multiprocessor.
? The more common multiprocessor systems incorporate on
The types of multiprocessor systems
? Multiprocessor systems may be classified into four types:
? single instruction stream, single data stream (SISD);
? single instruction steam, multiple data stream (SIMD);
? multiple instruction stream, single data stream (MISD); multiple instruction stream, multiple data stream (MIM
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