Unit 4 How PCs Work?ContentsLearning ObjectivesAfter you have read th
is unit, you should be familiar with:1. What CPU contains?2. The
system component of computer. Words&ExpressionsText The basic
building block of a modem computer is a chip, a complex, integrat
ed electronic circuit etched on a tiny square of silicon no bigge
r than a fingernail. Since individual chips are fragile and diffi
cult to handle, they are normally packed and mounted on boards. A
computer is assembled by sliding the right boards into a machine
box. One board might hold the processor, which in fact is the he
art of a computer; another might hold memory store which provides
the computer with data and instructions; while the third might h
old the electronics to link a particular input device or output d
evice to the system. Let us use the system shown in Figure2-6
to show you how a typical computer works. A computer is controlle
d by a stored program, so if weText want to use a computer, the f
irst step is copying the program from diskette into memory. Now t
he processor can begin executing instructions; the data input fro
m the keyboard are stored in memory. The processor processes the
data and then stores the results back into memory. At last, we ca
n get the result. Now we can see that a computer system consis
ts of four basic components. An input device provides data. The d
ata are stored in memory, which also holds a program. Under the c
ontrols of the program, the computer’s processor processes the da
ta. The results flow from the computer to an output device. Let u
s come closer to the system components one by one. Beginning with
the processor. The processor, usually called the central proc
essing unit (CPU) or main processor, is the heart of a computer.
It is the CPU that in fact processes or manipulates data and cont
rols all the rest parts of the computer. How can it manage its jo
b? The secret is software. Without a program to provide control,
a CPU can do nothing. How can a program guide the CPU through the
processes? Let us consider from the basic element of a program-i
nstruction. An instruction is composed of two parts: an operation
code and one or more operands (Figure 2-7). The operation code t
ells the CPU what to do and the operands tell the CPU where to fi
nd the data to be manipulated. The processor contains four maj
or components (Figure 2-8): a clock, an instruction control unit,
an arithmetic and logic unit (usually shorted forALU), and sever
al registers. The clock generates precisely timed pulses of curre
nt that synchronize the processor’s other components. Then the in
struction control unit determines the location of the next instru
ction to be executed and fetches it from the main memory. The ari
thmetic and logic unit performs arithmetic operations (such as ad
dition and subtraction) and logic operations (such as testing a v
alue to see if it is true or false), while the registers are temp
orary storage devices that hold control information, key data and
some intermediate results. Since the registers are located in th
e CPU, the processing speed is faster than the main memory. Then
which is the key component to a computer’s speed? It is the clock
! In more detail, it is the clock’s frequency that decides a comp
uter’s processing speed. When we buy a computer, we usuallyconsid
er the main frequency first, and that mean a clock’s frequency.
Now we will talk more in detail about the Microprocessors and C
entral Processing Units (Figure 2-9). Microprocessors are central
processing units etched on a tiny chip of silicon and, thus, are
called microchips. Microprocessors contain many electronic switc
hes, called transistors, which determine whether electric current
is allowed to pass through or not. Transistors are the basic bui
lding blocks of microprocessors. A single microchip may contain m
illions of transistors. When electric current is allowed to pass
through, the switch is on. This represents a 1 bit. If the curren
t does not pass through, the switch is off. This represents a 0 b
it. When we talk about the computer, we usually meet the topic
: motherboard. The main circuit board in a computer is called the
motherboard. It is a flat board the holds all of the key element
s that make up the “brain” of the system, including the microproc
essor or CPU, RAM (electronic or primary memory), and expansion s
lots which are sockets where other circuit boards called expansio
n boards may be plugged in.Exercises1. Answer the following ques
tion according to the text.(1) How PC works ?(2) How many basic c
omponents are there in a computer system?(3) What is CPU?(4) How
can it manage its job?2. Translate the following terms or phrase
s from English into Chinese and vice versa:key3. Fill in the bla
nks with the information given in the text: (1) The basic buildin
g block of a modem computer is a chip, a complex, integrated elec
tronic circuit etched on no bigger than a fingernail.(2)
The processor, usually called or , is the heart of a computer
. (3) An instruction is composed of two parts: an and one or mo
re operands.(4) Microprocessors are central processing units etch
ed on a tiny chip of silicon and, thus, are called .(
5) The main circuit board in a computer is called the .key4. C
hoose the best one from the items given below to complete the fol
lowing passage. Mobile computers-which (1) laptops, no
tebooks, subnotebooks and handholds (2) so ubiquitous in such
a short time, no surprise to hear who say: ”It will define the l
eading edge (3) the next five years or so.” The most remarkab
le (4) mobile computers is the amount of data storage and me
mory packed (5) their tiny boxes. These devices not only han
dle windows easily but also run storage-hungry programs.(1) A. in
cluded B. include C. includes D. have included(2) A. have beco
me B. had become C. becoming D. becomes(3) A. from B. for C. to
D. about(4) A. at B. to C. for D. above(5) A. under B. to
C. into D. ontokey5. Mark the following statements with T(true
) or F(false) according to the text.(1) Since individual chips a
re fragile and difficult to handle, they are normally packed and
mounted on boards.(2) The processor contains four major componen
ts: a clock, an instruction control unit, an arithmetic and logic
unit (usually shorted for ALU), and several registers.(3) When
electric current is allowed to pass through, the switch is on. Th
is represents a 0 bit. If the current does not pass through, the
switch is off. This represents a 1 bit.(4) it is the clock’s freq
uency that decides a computer’s processing speed. (5) The main c
ircuit board in a computer is called the motherboard. It is a fla
t board the holds all of the key elements that make up the “brain
” of the system.key6. Select the one answer to each question.(1)
A (n) gathers input and transforms it into a serie
s of electronic signals for the computer to store and manipulate.
A. output device B. input device C. memory
D. data(2) In a computer, most processing take place in a comp
onent called the .A. bus B. memory C
. system unit D. central processing unit(3) Random-access memor
y (RAM) is a kind of storage.A. permanent. B. te
mporaryC. Flash D. smart(4) ROM is a type of .A. semicond
uctor B. slot C. adapter D. network(5) A (n) typically co
mbines the capability of a scanner, printer, fax, and copying mac
hine.A. multifunctional device B. output deviceC. input device
D. CD-read only memory(6) is the area where data can be l
eft on a permanent basis when it is not immediately needed for pr
ocessing.A. Secondary storage B. CMOSC. CPU D. Primary storag
ekey7. Translate the following sentences into Chinese.(1) The ba
sic building block of a modem computer is a chip, a complex, inte
grated electronic circuit etched on a tiny square of silicon no b
igger than a fingernail.(2) The processor processes the data and
then stores the results back into memory. At last, we can get the
result.(3) Now we can see that a computer system consists of fou
r basic components. An input device provides data. The data are s
tored in memory, which also holds a program. Under the controls o
f the program, the computer’s processor processes the data. The r
esults flow from the computer to an output device.(4) The clock g
enerates precisely timed pulses of current that synchronize the processor’s other components.key1.略2.3. (1) a tiny square of silicon (2) the central processing unit (CPU) , main processor (3) operation code (4) microchips (5) motherboard4. (1) B (2) A (3) D (4) C (5) C5.(1) T (2) T (3) F (4) T (5) T6. (1) B (2) D (3) B (4) A (5) A (6) A7.(1) 芯片是构成现代计算机的基本器件。它是一个复杂的集成电子线路，蚀记得在一个比指甲还小的正方形硅片上。(2) 由处理器加工数据，然后把结果送回主存。最后，我们得到结果。(3) 现在我们看到计算机是由四个基本部件组成的：提供数据的输入设备；存放数据存储器（程序也保存在内）；在该程序的控制下处理数据的处理器；输出结果的输出设备。(4) 时钟精确地产生定时电流脉冲，使之与处理器的其他部件同步。 |
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