Number System
NUMBER SYSTEM-Computer uses the binary system. Any physical system that can exist in two distinct states (e.g., 0-1, on-off, hi-lo, yes-no, up-down, north-south, etc.) has the potential of being used to represent numbers or characters. A binary digit is called a bit. Thre are two possible states in a bit, usually expressed as 0 and 1.
A series of eight bits strung together makes a byte, much as 12 makes a dozen. With 8 bits, or 8 binary digits, there exist 2^8=256 possible combinations. The following table shows some of these combinations. (The number enclosed in parentheses represents the decimal equivalent.)
00000000 ( 0) 00010000 ( 16) 00100000 ( 32) ... 01110000 (112)
00000001 ( 1) 00010001 ( 17) 00100001 ( 33) ... 01110001 (113)
00000010 ( 2) 00010010 ( 18) 00100010 ( 34) ... 01110010 (114)
00000011 ( 3) 00010011 ( 19) 00100011 ( 35) ... 01110011 (115)
00000100 ( 4) 00010100 ( 20) 00100100 ( 36) ... 01110100 (116)
00000101 ( 5) 00010101 ( 21) 00100101 ( 37) ... 01110101 (117)
00000110 ( 6) 00010110 ( 22) 00100110 ( 38) ... 01110110 (118)
00000111 ( 7) 00010111 ( 23) 00100111 ( 39) ... 01110111 (119)
00001000 ( 8) 00011000 ( 24) 00101000 ( 40) ... 01111000 (120)
00001001 ( 9) 00011001 ( 25) 00101001 ( 41) ... 01111001 (121)
00001010 ( 10) 00011010 ( 26) 00101010 ( 42) ... 01111010 (122)
00001011 ( 11) 00011011 ( 27) 00101011 ( 43) ... 01111011 (123)
00001100 ( 12) 00011100 ( 28) 00101100 ( 44) ... 01111100 (124)
00001101 ( 13) 00011101 ( 29) 00101101 ( 45) ... 01111101 (125)
00001110 ( 14) 00011110 ( 30) 00101110 ( 46) ... 01111110 (126)
00001111 ( 15) 00011111 ( 31) 00101111 ( 47) ... 01111111 (127)
:
(continued)
:
10000000 (128) 10010000 (144) 10100000 (160) ... 11110000 (240)
10000001 (129) 10010001 (145) 10100001 (161) ... 11110001 (241)
10000010 (130) 10010010 (146) 10100010 (162) ... 11110010 (242)
10000011 (131) 10010011 (147) 10100011 (163) ... 11110011 (243)
10000100 (132) 10010100 (148) 10100100 (164) ... 11110100 (244)
10000101 (133) 10010101 (149) 10100101 (165) ... 11110101 (245)
10000110 (134) 10010110 (150) 10100110 begin_of_the_skype_highlighting (150) 10100110 end_of_the_skype_highlighting (166) ... 11110110 (246)
10000111 (135) 10010111 (151) 10100111 (167) ... 11110111 (247)
10001000 (136) 10011000 (152) 10101000 (168) ... 11111000 (248)
10001001 (137) 10011001 (153) 10101001 (169) ... 11111001 (249)
10001010 (138) 10011010 (154) 10101010 begin_of_the_skype_highlighting (154) 10101010 end_of_the_skype_highlighting (170) ... 11111010 (250)
10001011 (139) 10011011 (155) 10101011 begin_of_the_skype_highlighting (155) 10101011 end_of_the_skype_highlighting (171) ... 11111011 (251)
10001100 (140) 10011100 (156) 10101100 begin_of_the_skype_highlighting (156) 10101100 end_of_the_skype_highlighting (172) ... 11111100 (252)
10001101 (141) 10011101 (157) 10101101 begin_of_the_skype_highlighting (157) 10101101 end_of_the_skype_highlighting (173) ... 11111101 (253)
10001110 (142) 10011110 (158) 10101110 begin_of_the_skype_highlighting (158) 10101110 end_of_the_skype_highlighting (174) ... 11111110 (254)
10001111 (143) 10011111 (159) 10101111 (175) ... 11111111 (255)
________________________________________
K & M
2^10=1024 is commonly referred to as a "K". It is approximately equal to one thousand. Thus, 1 Kbyte is 1024 bytes. Likewise, 1024K is referred to as a "Meg". It is approximately equal to a million. 1 Mega byte is 1024*1024=1,048,576 bytes. If you remember that 1 byte equals one alphabetical letter, you can develop a good feel for size.
________________________________________
Number System
You may regard each digit as a box that can hold a number. In the binary system, there can be only two choices for this number -- either a "0" or a "1". In the octal system, there can be eight possibilities:
"0", "1", "2", "3", "4", "5", "6", "7".
In the decimal system, there are ten different numbers that can enter the digit box:
"0", "1", "2", "3", "4", "5", "6", "7", "8", "9".
In the hexadecimal system, we allow 16 numbers:
"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", and "F".
As demonstrated by the following table, there is a direct correspondence between the binary system and the octal system, with three binary digits corresponding to one octal digit. Likewise, four binary digits translate directly into one hexadecimal digit. In computer usage, hexadecimal notation is especially common because it easily replaces the binary notation, which is too long and human mistakes in transcribing the binary numbers are too easily made. Base Conversion Table
BIN OCT HEX DEC
----------------------
0000 00 0 0
0001 01 1 1
0010 02 2 2
0011 03 3 3
0100 04 4 4
0101 05 5 5
0110 06 6 6
0111 07 7 7
----------------------
1000 10 8 8
1001 11 9 9
1010 12 A 10
1011 13 B 11
1100 14 C 12
1101 15 D 13
1110 16 E 14
1111 17 F 15
________________________________________
Convert From Any Base To Decimal
Let's think more carefully what a decimal number means. For example, 1234 means that there are four boxes (digits); and there are 4 one's in the right-most box (least significant digit), 3 ten's in the next box, 2 hundred's in the next box, and finally 1 thousand's in the left-most box (most significant digit). The total is 1234:
Original Number: 1 2 3 4
How Many Tokens: 1 2 3 4
Digit/Token Value: 1000 100 10 1
Value: 1000 + 200 + 30 + 4 = 1234
or simply, 1*1000 + 2*100 + 3*10 + 4*1 = 1234
Thus, each digit has a value: 10^0=1 for the least significant digit, increasing to 10^1=10, 10^2=100, 10^3=1000, and so forth. Likewise, the least significant digit in a hexadecimal number has a value of 16^0=1 for the least significant digit, increasing to 16^1=16 for the next digit, 16^2=256 for the next, 16^3=4096 for the next, and so forth. Thus, 1234 means that there are four boxes (digits); and there are 4 one's in the right-most box (least significant digit), 3 sixteen's in the next box, 2 256's in the next, and 1 4096's in the left-most box (most significant digit). The total is:
1*4096 + 2*256 + 3*16 + 4*1 = 4660
Example. Convert the hexadecimal number 4B3 to decimal notation. What about the decimal equivalent of the hexadecimal number 4B3.3?
Solution:
Original Number: 4 B 3 . 3
How Many Tokens: 4 11 3 3
Digit/Token Value: 256 16 1 0.0625
Value: 1024 +176 + 3 + 0.1875 = 1203.1875
Example. Convert 234.14 expressed in an octal notation to decimal.
Solution:
Original Number: 2 3 4 . 1 4
How Many Tokens: 2 3 4 1 4
Digit/Token Value: 64 8 1 0.125 0.015625
Value: 128 + 24 + 4 + 0.125 + 0.0625 = 156.1875
Another way is to think of a cash register with different slots, each holding bills of a different denomination.
________________________________________
Convert From Decimal to Any Base
Again, let's think about what you do to obtain each digit. As an example, let's start with a decimal number 1234 and convert it to decimal notation. To extract the last digit, you move the decimal point left by one digit, which means that you divide the given number by its base 10.
1234/10 = 123 + 4/10
The remainder of 4 is the last digit. To extract the next last digit, you again move the decimal point left by one digit and see what drops out.
123/10 = 12 + 3/10
The remainder of 3 is the next last digit. You repeat this process until there is nothing left. Then you stop. In summary, you do the following:
Quotient Remainder
-----------------------------
1234/10 = 123 4 --------+
123/10 = 12 3 ------+
12/10 = 1 2 ----+
1/10 = 0 1 --+
(Stop when the quotient is 0.)
1 2 3 4 (Base 10)
Now, let's try a nontrivial example. Let's express a decimal number 1341 in binary notation. Note that the desired base is 2, so we repeatedly divide the given decimal number by 2.
Quotient Remainder
-----------------------------
1341/2 = 670 1 ----------------------+
670/2 = 335 0 --------------------+
335/2 = 167 1 ------------------+
167/2 = 83 1 ----------------+
83/2 = 41 1 --------------+
41/2 = 20 1 ------------+
20/2 = 10 0 ----------+
10/2 = 5 0 --------+
5/2 = 2 1 ------+
2/2 = 1 0 ----+
1/2 = 0 1 --+
(Stop when the quotient is 0)
1 0 1 0 0 1 1 1 1 0 1 (BIN; Base 2)
Let's express the same decimal number 1341 in octal notation.
Quotient Remainder
-----------------------------
1341/8 = 167 5 --------+
167/8 = 20 7 ------+
20/8 = 2 4 ----+
2/8 = 0 2 --+
(Stop when the quotient is 0)
2 4 7 5 (OCT; Base 8)
Let's express the same decimal number 1341 in hexadecimal notation.
Quotient Remainder
-----------------------------
1341/16 = 83 13 ------+
83/16 = 5 3 ----+
5/16 = 0 5 --+
(Stop when the quotient is 0)
5 3 D (HEX; Base 16)
Example. Convert the decimal number 3315 to hexadecimal notation. What about the hexadecimal equivalent of the decimal number 3315.3?
Solution:
Quotient Remainder
-----------------------------
3315/16 = 207 3 ------+
207/16 = 12 15 ----+
12/16 = 0 12 --+
(Stop when the quotient is 0)
C F 3 (HEX; Base 16)
(HEX; Base 16)
Product Integer Part 0.4 C C C ...
--------------------------------
0.3*16 = 4.8 4 ----+
0.8*16 = 12.8 12 ------+
0.8*16 = 12.8 12 --------+
0.8*16 = 12.8 12 ----------+
: ---------------------+
:
Thus, 3315.3 (DEC) --> CF3.4CCC... (HEX)
________________________________________
Note that from the Base Conversion Table, you can easily get the binary notation from the hexadecimal number by grouping four binary digits per hexadecimal digit, or from or the octal number by grouping three binary digits per octal digit, and vice versa.
HEX 5 3 D
BIN 0101 0011 1101
OCT 2 4 7 5
BIN 010 100 111 101
Finally, the fractional part is a decimal number can also be converted to any base by repeatedly multiplying the given number by the target base. Example: Convert a decimal number 0.1234 to binary notation
(BIN; Base 2)
Product Integer Part 0.0 0 0 1 1 1 1 1 1 0 0 1 ...
--------------------------------
0.1234*2 = 0.2468 0 ----+
0.2468*2 = 0.4936 0 ------+
0.4936*2 = 0.9872 0 --------+
0.9872*2 = 1.9744 1 ----------+
0.9744*2 = 1.9488 1 ------------+
0.9488*2 = 1.8976 1 --------------+
0.8976*2 = 1.7952 1 ----------------+
0.7952*2 = 1.5904 1 ------------------+
0.5904*2 = 1.1808 1 --------------------+
0.1808*2 = 0.3616 0 ----------------------+
0.3616*2 = 0.7232 0 ------------------------+
0.7232*2 = 1.4464 1 --------------------------+
: ----------------------------+
:
________________________________________
Additon and Multiplication Tables
You generate the addition tables in bases other then 10 by following the same rule you do in base 10. The resulting tables have the appearance of shifting the columns to the left by one in each subsequent rows. Note how simple the addition and multiplication tables are for the binary system; addition operation is simply the bit-wise XOR operation with carry, and multiplication is simply the logical AND operation.
Decimal Addition Table:
0 1 2 3 4 5 6 7 8 9
---+-----------------------------
0
0 1 2 3 4 5 6 7 8 9
1
1 2 3 4 5 6 7 8 9 10
2
2 3 4 5 6 7 8 9 10 11
3
3 4 5 6 7 8 9 10 11 12
4
4 5 6 7 8 9 10 11 12 13
5
5 6 7 8 9 10 11 12 13 14
6
6 7 8 9 10 11 12 13 14 15
7
7 8 9 10 11 12 13 14 15 16
8
8 9 10 11 12 13 14 15 16 17
9
9 10 11 12 13 14 15 16 17 18
Binary Addition Table:
0 1
---+-----
0
0 1
1
1 10
Octal Addition Table:
0 1 2 3 4 5 6 7
---+-----------------------
0
0 1 2 3 4 5 6 7
1
1 2 3 4 5 6 7 10
2
2 3 4 5 6 7 10 11
3
3 4 5 6 7 10 11 12
4
4 5 6 7 10 11 12 13
5
5 6 7 10 11 12 13 14
6
6 7 10 11 12 13 14 15
7
7 10 11 12 13 14 15 16
Hexadecimal Addition Table:
0 1 2 3 4 5 6 7 8 9 A B C D E F
---+-----------------------------------------------
0
0 1 2 3 4 5 6 7 8 9 A B C D E F
1
1 2 3 4 5 6 7 8 9 A B C D E F 10
2
2 3 4 5 6 7 8 9 A B C D E F 10 11
3
3 4 5 6 7 8 9 A B C D E F 10 11 12
4
4 5 6 7 8 9 A B C D E F 10 11 12 13
5
5 6 7 8 9 A B C D E F 10 11 12 13 14
6
6 7 8 9 A B C D E F 10 11 12 13 14 15
7
7 8 9 A B C D E F 10 11 12 13 14 15 16
8
8 9 A B C D E F 10 11 12 13 14 15 16 17
9
9 A B C D E F 10 11 12 13 14 15 16 17 18
A
A B C D E F 10 11 12 13 14 15 16 17 18 19
B
B C D E F 10 11 12 13 14 15 16 17 18 19 1A
C
C D E F 10 11 12 13 14 15 16 17 18 19 1A 1B
D
D E F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C
E
E F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D
F
F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E
You can also generate multiplication tables in bases other than 10 by following the same rule you do in base 10.
Decimal Multiplication Table:
0 1 2 3 4 5 6 7 8 9
---+-----------------------------
0
0 0 0 0 0 0 0 0 0 0
1
0 1 2 3 4 5 6 7 8 9
2
0 2 4 6 8 10 12 14 16 18
3
0 3 6 9 12 15 18 21 24 27
4
0 4 8 12 16 20 24 28 32 36
5
0 5 10 15 20 25 30 35 40 45
6
0 6 12 18 24 30 36 42 48 54
7
0 7 14 21 28 35 42 49 56 63
8
0 8 16 24 32 40 48 56 64 72
9
0 9 18 27 36 45 54 63 72 81
Binary Multiplication Table:
0 1
---+-----
0
0 0
1
0 1
Octal Multiplication Table:
0 1 2 3 4 5 6 7
---+-----------------------
0
0 0 0 0 0 0 0 0
1
0 1 2 3 4 5 6 7
2
0 2 4 6 10 12 14 16
3
0 3 6 11 14 17 22 25
4
0 4 10 14 20 24 30 34
5
0 5 12 17 24 31 36 43
6
0 6 14 22 30 36 44 52
7
0 7 16 25 34 43 52 61
Hexadecimal Multiplication Table:
0 1 2 3 4 5 6 7 8 9 A B C D E F
---+-----------------------------------------------
0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1
0 1 2 3 4 5 6 7 8 9 A B C D E F
2
0 2 4 6 8 A C E 10 12 14 16 18 1A 1C 1E
3
0 3 6 9 C F 12 15 18 1B 1E 21 24 27 2A 2D
4
0 4 8 C 10 14 18 1C 20 24 28 2C 30 34 38 3C
5
0 5 A F 14 19 1E 23 28 2D 32 37 3C 41 46 4B
6
0 6 C 12 18 1E 24 2A 30 36 3C 42 48 4E 54 5A
7
0 7 E 15 1C 23 2A 31 38 3F 46 4D 54 5B 62 69
8
0 8 10 18 20 28 30 38 40 48 50 58 60 68 70 78
9
0 9 12 1B 24 2D 36 3F 48 51 5A 63 6C 75 7E 87
A
0 A 14 1E 28 32 3C 46 50 5A 64 6E 78 82 8C 96
B
0 B 16 21 2C 37 42 4D 58 63 6E 79 84 8F 9A A5
C
0 C 18 24 30 3C 48 54 60 6C 78 84 90 9C A8 B4
D
0 D 1A 27 34 41 4E 5B 68 75 82 8F 9C A9 B6 C3
E
0 E 1C 2A 38 46 54 62 70 7E 8C 9A A8 B6 C4 D2
F
0 F 1E 2D 3C 4B 5A 69 78 87 96 A5 B4 C3 D2 E1
________________________________________
Arithmetic Operations
You do arithematic with hexadecimal numbers or numbers in any base in exactly the same way you do with decimal numbers, except that the addition and multiplcation tables you employ to base your calculations are a bit different. Substraction is equivalent to adding a negative number, and division is equivalent to multiplying by the inverse.
Example. Find the sum of two hexadecimal integers 123 and DEF.
Solution:
From the above hexadecimal addition table, we see that:
3+F=12, 2+E=10, and 1+D=E
123
+ DEF
-----
carry 11
E02
-----
sum F12
Example. Find the product of two hexadecimal integers 123 and DEF.
Solution:
Step 1: We break down the second multiplier into single digits.
123*DEF = 123*(D00+E0+F)
= (123*D)*100 + (123*E)*10 + (123*F)
Step 2: We find the product in parentheses.
From the above hexadecimal multiplication table, we see that:
1*D=D, 2*D=1A, 3*D=27; thus,
123*D = (100+20+3)*D
= 1*D*100 + 2*D*10 + 3*D
= D*100 + 1A*10 + 27
= D00 + 1A0 + 27
= EC7
Likewise,
123*E = (100+20+3)*E
= 1*E*100 + 2*E*10 + 3*E
= E*100 + 1C*10 + 2A
= E00 + 1C0 + 2A
= FEA
123*F = (100+20+3)*F
= 1*F*100 + 2*F*10 + 3*F
= F*100 + 1E*10 + 2D
= F00 + 1E0 + 2D
= 110D
Or, in elementary school style:
123 123 123
x D x E x F
----- ----- -----
27 2A 2D
1A 1C 1E
D E F
----- ----- -----
EC7 FEA 110D
Step 3: We sum up the individual products.
123*DEF = (123*D)*100 + (123*E)*10 + (123*F)
= EC7*100 + FEA*10 + 110D
= EC700 + FEA0 + 110D
= FD6AD
Or, in elementary school style:
123
x DEF
-----
110D
FEA
EC7
-----
FD6AD
Tuesday, August 17, 2010
Thursday, August 12, 2010
ACTIVITY 3
List the Common 5 most common types of computer systems
Modern computers are electronic and process digital information. The physical machine
consists of transistors, digital circuits implemented with transistors, wires, and
mechanical components in peripheral devices used for information storage. These
physical entities are collectively called hardware. System and application programs are
called software. A general purpose computer system is a programmable machine that can
solve problems by accepting inputs and instructions on how to use these inputs. The
instructions are included in computer programs (that is, software) that normally contain
sequences of them. Graphical languages are rarely used to represent computer programs
as collections of instructions with relationships between arbitrary pairs of them.
Programs are often written in high- level languages (HLLs) that have to be translated (by
appropriate software compilers) to produce machine-readable (that is, machine language)
code that can be run directly by the given computer system. The machine language code
contains sequences of primitive instructions for the given computer in binary
representation. On the other hand, HLLs employ mnemonics of more powerful
instructions, and appropriate structures to make programming easy and independent of
the target computer.
From the software point of view, a computer is a six- level system consisting of the digital
logic (collections of electronic gates), microarchitecture (a collection of functional units,
such as ALUs - Arithmetic Logic Units, and their interconnectivity), instruction set
architecture (the complete set of machine language instructions), operating system (code
that monitors and controls the activities of the computer), assembly and machine
language, and high-level language. The assembly language is very close to the machine
language of a computer; it basically replaces the binary representation of machine
instructions with mnemonics in a one-to-one fashion. From the hardware point of view, a
computer is conveniently assumed to be a five- level hierarchy. The five levels correspond
to network ports for connecting to the outside world (these ports may not be necessarily
available, as a computer may be a standalone information processing and/or computing
machine), peripheral or mass-storage devices for (applications and system) program and
data storage, main memory, program and data caches (fast memories for retrieving data
by content), and CPU (Central Processing Unit) or processor. Specia l emphasis is given
in this article to the description of computer systems based on this five-level
representation. Many other components are also included in computer systems in order to
enable the aforementioned basic components to function properly. For example, control
and data busses are used to transmit data between any two successive levels of the
hardware hierarchy and glue logic is used to implement the appropriate interfaces. The
design of a computer system most often begins with the selection of a particular CPU.
The other components are selected progressively based on performance requirements.
Analytical techniques, software simulations, and software or hardware prototyping of the
complete or partial computer system are used to make final decisio ns about the design.
Special attention is given nowadays to hardware-software codesign, where the selection
or design of components is made in unison with the development of the corresponding
system software.
There exist several types of general purpose computer systems. These types are grouped
together into two major computer classes, comprising sequential or conventional
computers, and parallel computers, respectively. The class of sequential or conventional
computer systems comprises:
· Supercomputers.
The fastest type of computer. Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, fluid dynamic calculations, nuclear energy, and petroleum exploration.
The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently.
· PCs (personal computers) or desktops.
These computers also are of the
microcomputer type. Figure 1 shows the basic components of a microcomputer. The
RAM and ROM form the main memory that stores system and application programs, and
data. The ROM contains only part of the operating system, and most often the part that
initializes the computer. The sofware stored in the ROM is called firmware. Resource
interface units form the required glue logic for the implementation of the required data
exchange protocols. The control bus transfers the control signals produced by the
microprocessor. To access an element in the memory or a peripheral device, the
microprocessor first issues the address of that item on the address bus. The address bus is
unidirectional, from the processor to the other units. While the latter value is still present
on the address bus, the microprocessor issues the appropriate control signals to read or
write from the corresponding location. The address issued by the microprocessor is
decoded by external logic to choose the appropriate memory module or I/O device. The
data is finally transferred on the bidirectional data bus. Details on how microcomputers
execute programs are presented in Section 2.
· Workstations.
A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has also been used to refer to a mainframe computer terminal or a PC connected to a network.
Historically, workstations had offered higher performance than personal computers, especially with respect to CPU and graphics, memory capacity and multitasking capability. They are optimized for the visualization and manipulation of different types of complex data such as 3D mechanical design, engineering simulation (e.g. computational fluid dynamics), animation and rendering of images, and mathematical plots. Consoles consist of a high resolution display, a keyboard and a mouse at a minimum, but also offer multiple displays, graphics tablets, 3D mice (devices for manipulating and navigating 3D objects and scenes), etc. Workstations are the first segment of the computer market to present advanced accessories and collaboration tools.
Presently, the workstation market is highly commoditized and is dominated by large PC vendors, such as Dell and HP, selling Microsoft Windows/Linux running on Intel Xeon/AMD Opteron. Alternative UNIX based platforms are provided by Apple Inc., Sun Microsystems, and SGI.
· Minicomputers.
High-performance cabinet-sized computers that can be used
simultaneously by a few dozens of users. They are often used in engineering and
scientific ap
They appeared in the 1980s as single-user computers with much
better performance than PCs, primarily because they contain very advanced
microprocessors. They often include proprietary co-processors to facilitate graphics
functions because they basically target the scientific and engineering communities. They
were uniprocessor computers in the early days, but multiprocessor workstations appeared
for the first time in the market a few years ago. They are now often used as multi-user
platforms.
plications. They have been replaced recently by advanced workstations and
networks of workstations.
· Mainframes.
Very powerful computers that can serve many dozens or hundreds
of users simultaneously. IBM has produced numerous computers of this type. They have
been replaced recently in many occasions by networks of workstations.
Describe a typical use for mainframe computers
Mainframes are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry/consumer statistics, ERP, and financial transaction processing.
The term originated during the early years of computing and referred to the large mechanical assembly that held the central processor and input/output complex. Later the term was used to distinguish high-end commercial machines from less powerful units which were often contained in smaller packages. Today, this term almost exclusively refers to IBM System z9 mainframes, the lineal descendants of the System/360.
Differentiate Workstation from personal computers
A work station may not, necessarily, have all of the components located in one physical space.
As part of a network the work station may connect to a server to access databases, printers, etc.
A PC is usually a self contained system, that includes all components and peripherals
Identify types of personal computer
Workstation
Sun SPARCstation 1+, 25 MHz RISC processor from early 1990s
Main article: Workstation
A workstation is a high-end personal computer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. Workstations are used for tasks such as computer-aided design, drafting and modelling, computation-intensive scientific and engineering calculations, image processing, architectural modelling, and computer graphics for animation and motion picture visual effects.
Desktop computer
Dell OptiPlex desktop computer
Prior to the wide spread of PCs a computer that could fit on a desk was considered remarkably small. Today the phrase usually indicates a particular style of computer case. Desktop computers come in a variety of styles ranging from large vertical tower cases to small form factor models that can be tucked behind an LCD monitor. In this sense, the term 'desktop' refers specifically to a horizontally-oriented case, usually intended to have the display screen placed on top to save space on the desk top. Most modern desktop computers have separate screens and keyboards.
Single unit
Single unit PCs (also known as all-in-one PCs) are a subtype of desktop computers, which combine the monitor and case of the computer within a single unit. The monitor often utilizes a touchscreen as an optional method of user input, however detached keyboards and mice are normally still included. The inner components of the PC are often located directly behind the monitor, and many are built similarly to laptops.
A mid-range HP Laptop.
A laptop computer or simply laptop, also called a notebook computer or sometimes a notebook, is a small personal computer designed for portability. Usually all of the interface hardware needed to operate the laptop, such as USB ports (previously parallel and serial ports), graphics card, sound channel, etc., are built in to a single unit. Laptops contain high capacity batteries that can power the device for extensive periods of time, enhancing portability. Once the battery charge is depleted, it will have to be recharged through a power outlet. In the interest of saving power, weight and space, they usually share RAM with the video channel, slowing their performance compared to an equivalent desktop machine.
One main drawback of the laptop is sometimes, due to the size and configuration of components, relatively little can be done to upgrade the overall computer from its original design. Internal upgrades are either not manufacturer recommended, can damage the laptop if done with poor care or knowledge, or in some cases impossible, making the desktop PC more modular. Some internal upgrades, such as memory and hard disks upgrades are often easy, a display or keyboard upgrade is usually impossible. The laptop has the same access as the desktop to the wide variety of devices, such as external displays, mice, cameras, storage devices and keyboards, which may be attached externally through USB ports and other less common ports such as external video.
A subtype of notebooks, called subnotebooks, are computers with most of the features of a standard laptop computer but smaller. They are larger than hand-held computers, and usually run full versions of desktop/laptop operating systems. Ultra-Mobile PCs (UMPC) are usually considered subnotebooks, or more specifically, subnotebook Tablet PCs (see below). Netbooks are sometimes considered in this category, though they are sometimes separated in a category of their own (see below).
Desktop replacements, meanwhile, are large laptops meant to replace a desktop computer while keeping the mobility of a laptop. Entertainment laptops emphasize large, HDTV-resolution screens and video processing capabilities.
Pocket PC
An O2 pocket PC
A pocket PC is a hardware specification for a handheld-sized computer (personal digital assistant) that runs the Microsoft Windows Mobile operating system. It may have the capability to run an alternative operating system like NetBSD or Linux. It has many of the capabilities of modern desktop PCs.
Currently there are tens of thousands of applications for handhelds adhering to the Microsoft Pocket PC specification, many of which are freeware. Some of these devices also include mobile phone features. Microsoft compliant Pocket PCs can also be used with many other add-ons like GPS receivers, barcode readers, RFID readers, and cameras. In 2007, with the release of Windows Mobile 6, Microsoft dropped the name
Modern computers are electronic and process digital information. The physical machine
consists of transistors, digital circuits implemented with transistors, wires, and
mechanical components in peripheral devices used for information storage. These
physical entities are collectively called hardware. System and application programs are
called software. A general purpose computer system is a programmable machine that can
solve problems by accepting inputs and instructions on how to use these inputs. The
instructions are included in computer programs (that is, software) that normally contain
sequences of them. Graphical languages are rarely used to represent computer programs
as collections of instructions with relationships between arbitrary pairs of them.
Programs are often written in high- level languages (HLLs) that have to be translated (by
appropriate software compilers) to produce machine-readable (that is, machine language)
code that can be run directly by the given computer system. The machine language code
contains sequences of primitive instructions for the given computer in binary
representation. On the other hand, HLLs employ mnemonics of more powerful
instructions, and appropriate structures to make programming easy and independent of
the target computer.
From the software point of view, a computer is a six- level system consisting of the digital
logic (collections of electronic gates), microarchitecture (a collection of functional units,
such as ALUs - Arithmetic Logic Units, and their interconnectivity), instruction set
architecture (the complete set of machine language instructions), operating system (code
that monitors and controls the activities of the computer), assembly and machine
language, and high-level language. The assembly language is very close to the machine
language of a computer; it basically replaces the binary representation of machine
instructions with mnemonics in a one-to-one fashion. From the hardware point of view, a
computer is conveniently assumed to be a five- level hierarchy. The five levels correspond
to network ports for connecting to the outside world (these ports may not be necessarily
available, as a computer may be a standalone information processing and/or computing
machine), peripheral or mass-storage devices for (applications and system) program and
data storage, main memory, program and data caches (fast memories for retrieving data
by content), and CPU (Central Processing Unit) or processor. Specia l emphasis is given
in this article to the description of computer systems based on this five-level
representation. Many other components are also included in computer systems in order to
enable the aforementioned basic components to function properly. For example, control
and data busses are used to transmit data between any two successive levels of the
hardware hierarchy and glue logic is used to implement the appropriate interfaces. The
design of a computer system most often begins with the selection of a particular CPU.
The other components are selected progressively based on performance requirements.
Analytical techniques, software simulations, and software or hardware prototyping of the
complete or partial computer system are used to make final decisio ns about the design.
Special attention is given nowadays to hardware-software codesign, where the selection
or design of components is made in unison with the development of the corresponding
system software.
There exist several types of general purpose computer systems. These types are grouped
together into two major computer classes, comprising sequential or conventional
computers, and parallel computers, respectively. The class of sequential or conventional
computer systems comprises:
· Supercomputers.
The fastest type of computer. Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, fluid dynamic calculations, nuclear energy, and petroleum exploration.
The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently.
· PCs (personal computers) or desktops.
These computers also are of the
microcomputer type. Figure 1 shows the basic components of a microcomputer. The
RAM and ROM form the main memory that stores system and application programs, and
data. The ROM contains only part of the operating system, and most often the part that
initializes the computer. The sofware stored in the ROM is called firmware. Resource
interface units form the required glue logic for the implementation of the required data
exchange protocols. The control bus transfers the control signals produced by the
microprocessor. To access an element in the memory or a peripheral device, the
microprocessor first issues the address of that item on the address bus. The address bus is
unidirectional, from the processor to the other units. While the latter value is still present
on the address bus, the microprocessor issues the appropriate control signals to read or
write from the corresponding location. The address issued by the microprocessor is
decoded by external logic to choose the appropriate memory module or I/O device. The
data is finally transferred on the bidirectional data bus. Details on how microcomputers
execute programs are presented in Section 2.
· Workstations.
A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has also been used to refer to a mainframe computer terminal or a PC connected to a network.
Historically, workstations had offered higher performance than personal computers, especially with respect to CPU and graphics, memory capacity and multitasking capability. They are optimized for the visualization and manipulation of different types of complex data such as 3D mechanical design, engineering simulation (e.g. computational fluid dynamics), animation and rendering of images, and mathematical plots. Consoles consist of a high resolution display, a keyboard and a mouse at a minimum, but also offer multiple displays, graphics tablets, 3D mice (devices for manipulating and navigating 3D objects and scenes), etc. Workstations are the first segment of the computer market to present advanced accessories and collaboration tools.
Presently, the workstation market is highly commoditized and is dominated by large PC vendors, such as Dell and HP, selling Microsoft Windows/Linux running on Intel Xeon/AMD Opteron. Alternative UNIX based platforms are provided by Apple Inc., Sun Microsystems, and SGI.
· Minicomputers.
High-performance cabinet-sized computers that can be used
simultaneously by a few dozens of users. They are often used in engineering and
scientific ap
They appeared in the 1980s as single-user computers with much
better performance than PCs, primarily because they contain very advanced
microprocessors. They often include proprietary co-processors to facilitate graphics
functions because they basically target the scientific and engineering communities. They
were uniprocessor computers in the early days, but multiprocessor workstations appeared
for the first time in the market a few years ago. They are now often used as multi-user
platforms.
plications. They have been replaced recently by advanced workstations and
networks of workstations.
· Mainframes.
Very powerful computers that can serve many dozens or hundreds
of users simultaneously. IBM has produced numerous computers of this type. They have
been replaced recently in many occasions by networks of workstations.
Describe a typical use for mainframe computers
Mainframes are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry/consumer statistics, ERP, and financial transaction processing.
The term originated during the early years of computing and referred to the large mechanical assembly that held the central processor and input/output complex. Later the term was used to distinguish high-end commercial machines from less powerful units which were often contained in smaller packages. Today, this term almost exclusively refers to IBM System z9 mainframes, the lineal descendants of the System/360.
Differentiate Workstation from personal computers
A work station may not, necessarily, have all of the components located in one physical space.
As part of a network the work station may connect to a server to access databases, printers, etc.
A PC is usually a self contained system, that includes all components and peripherals
Identify types of personal computer
Workstation
Sun SPARCstation 1+, 25 MHz RISC processor from early 1990s
Main article: Workstation
A workstation is a high-end personal computer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. Workstations are used for tasks such as computer-aided design, drafting and modelling, computation-intensive scientific and engineering calculations, image processing, architectural modelling, and computer graphics for animation and motion picture visual effects.
Desktop computer
Dell OptiPlex desktop computer
Prior to the wide spread of PCs a computer that could fit on a desk was considered remarkably small. Today the phrase usually indicates a particular style of computer case. Desktop computers come in a variety of styles ranging from large vertical tower cases to small form factor models that can be tucked behind an LCD monitor. In this sense, the term 'desktop' refers specifically to a horizontally-oriented case, usually intended to have the display screen placed on top to save space on the desk top. Most modern desktop computers have separate screens and keyboards.
Single unit
Single unit PCs (also known as all-in-one PCs) are a subtype of desktop computers, which combine the monitor and case of the computer within a single unit. The monitor often utilizes a touchscreen as an optional method of user input, however detached keyboards and mice are normally still included. The inner components of the PC are often located directly behind the monitor, and many are built similarly to laptops.
A mid-range HP Laptop.
A laptop computer or simply laptop, also called a notebook computer or sometimes a notebook, is a small personal computer designed for portability. Usually all of the interface hardware needed to operate the laptop, such as USB ports (previously parallel and serial ports), graphics card, sound channel, etc., are built in to a single unit. Laptops contain high capacity batteries that can power the device for extensive periods of time, enhancing portability. Once the battery charge is depleted, it will have to be recharged through a power outlet. In the interest of saving power, weight and space, they usually share RAM with the video channel, slowing their performance compared to an equivalent desktop machine.
One main drawback of the laptop is sometimes, due to the size and configuration of components, relatively little can be done to upgrade the overall computer from its original design. Internal upgrades are either not manufacturer recommended, can damage the laptop if done with poor care or knowledge, or in some cases impossible, making the desktop PC more modular. Some internal upgrades, such as memory and hard disks upgrades are often easy, a display or keyboard upgrade is usually impossible. The laptop has the same access as the desktop to the wide variety of devices, such as external displays, mice, cameras, storage devices and keyboards, which may be attached externally through USB ports and other less common ports such as external video.
A subtype of notebooks, called subnotebooks, are computers with most of the features of a standard laptop computer but smaller. They are larger than hand-held computers, and usually run full versions of desktop/laptop operating systems. Ultra-Mobile PCs (UMPC) are usually considered subnotebooks, or more specifically, subnotebook Tablet PCs (see below). Netbooks are sometimes considered in this category, though they are sometimes separated in a category of their own (see below).
Desktop replacements, meanwhile, are large laptops meant to replace a desktop computer while keeping the mobility of a laptop. Entertainment laptops emphasize large, HDTV-resolution screens and video processing capabilities.
Pocket PC
An O2 pocket PC
A pocket PC is a hardware specification for a handheld-sized computer (personal digital assistant) that runs the Microsoft Windows Mobile operating system. It may have the capability to run an alternative operating system like NetBSD or Linux. It has many of the capabilities of modern desktop PCs.
Currently there are tens of thousands of applications for handhelds adhering to the Microsoft Pocket PC specification, many of which are freeware. Some of these devices also include mobile phone features. Microsoft compliant Pocket PCs can also be used with many other add-ons like GPS receivers, barcode readers, RFID readers, and cameras. In 2007, with the release of Windows Mobile 6, Microsoft dropped the name
Wednesday, August 11, 2010
activity 1
Information cycle is the progression of events over time as being processed by media. For example, a story (event) goes through a series of stages as it evolves by media; presented first by the Web, TV, Radio, newspapers, magazines, scholarly journals, and eventually comes into books.
data was created for the purpose of obtaining equality and justice for Africa through debt relief, adjusting tradeInformation cycle is the progression of events over time as being processed by media. For example, a story (event) goes through a series of stages as it evolves by media; presented first by the Web, TV, Radio, newspapers, magazines, scholarly journals, and eventually comes into books.
rules which burden Africa, eliminating the African AIDS epidemic, strengthening democracy, more accountability by the wealthiest nations and African leaders and transparency towards the people. In 2007, DATA and Bono were jointly awarded the National Constitution Center's 2007 Liberty Medal for their groundbreaking efforts to address the AIDS crisis and extreme poverty in Africa.
Start-up funds came from the Bill & Melinda Gates Foundation, financier George Soros, and technology entrepreneur Edward W. Scott.[1]
In 2007, DATA and the ONE Campaign decided to join forces, and in January 2008, they formally merged under the name ONE.[2]
DATA received support from the Christian rock/Alternative rock bands Switchfoot and Third Day.
Information, in its most restricted technical sense, is an ordered sequence of symbols. As a concept, however, information has many meanings.[1] Moreover, the concept of information is closely related to notions of constraint, communication, control, form, instruction, knowledge, meaning, mental stimulus, pattern, perception, and representation.
Tuesday, August 10, 2010
activity 2
Computer Components:
Computers are made of the following basic components:
Case with hardware inside:
Power Supply - The power supply comes with the case, but this component is mentioned separately since there are various types of power supplies. The one you should get depends on the requirements of your system. This will be discussed in more detail later
Motherboard - This is where the core components of your computer reside which are listed below. Also the support cards for video, sound, networking and more are mounted into this board.
Microprocessor - This is the brain of your computer. It performs commands and instructions and controls the operation of the computer.
Memory - The RAM in your system is mounted on the motherboard. This is memory that must be powered on to retain its contents.
Drive controllers - The drive controllers control the interface of your system to your hard drives. The controllers let your hard drives work by controlling their operation. On most systems, they are included on the motherboard, however you may add additional controllers for faster or other types of drives.
Hard disk drive(s) - This is where your files are permanently stored on your computer. Also, normally, your operating system is installed here.
CD-ROM drive(s) - This is normally a read only drive where files are permanently stored. There are now read/write CD-ROM drives that use special software to allow users to read from and write to these drives.
Floppy drive(s) - A floppy is a small disk storage device that today typically has about 1.4 Megabytes of memory capacity.
Other possible file storage devices include DVD devices, Tape backup devices, and some others.
Monitor - This device which operates like a TV set lets the user see how the computer is responding to their commands.
Keyboard - This is where the user enters text commands into the computer.
Mouse - A point and click interface for entering commands which works well in graphical environments.
These various parts will be discussed in the following sections.
Computers are made of the following basic components:
Case with hardware inside:
Power Supply - The power supply comes with the case, but this component is mentioned separately since there are various types of power supplies. The one you should get depends on the requirements of your system. This will be discussed in more detail later
Motherboard - This is where the core components of your computer reside which are listed below. Also the support cards for video, sound, networking and more are mounted into this board.
Microprocessor - This is the brain of your computer. It performs commands and instructions and controls the operation of the computer.
Memory - The RAM in your system is mounted on the motherboard. This is memory that must be powered on to retain its contents.
Drive controllers - The drive controllers control the interface of your system to your hard drives. The controllers let your hard drives work by controlling their operation. On most systems, they are included on the motherboard, however you may add additional controllers for faster or other types of drives.
Hard disk drive(s) - This is where your files are permanently stored on your computer. Also, normally, your operating system is installed here.
CD-ROM drive(s) - This is normally a read only drive where files are permanently stored. There are now read/write CD-ROM drives that use special software to allow users to read from and write to these drives.
Floppy drive(s) - A floppy is a small disk storage device that today typically has about 1.4 Megabytes of memory capacity.
Other possible file storage devices include DVD devices, Tape backup devices, and some others.
Monitor - This device which operates like a TV set lets the user see how the computer is responding to their commands.
Keyboard - This is where the user enters text commands into the computer.
Mouse - A point and click interface for entering commands which works well in graphical environments.
These various parts will be discussed in the following sections.
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