Summary 1 13=D 1 1 1 0 14=E 1

Summary of
Chapter#1: Data Storage

Bits and Their Storage: Information
in form of 0’s & 1’s is called “bits” (short form of
Binary Digits). The bit ‘0’ stands for False Value/Off state and the
other one represents True Value/On state.

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            The operations that utilize these
values are known as “Boolean Operations”. Some basic operations of theme
are OR, AND, NOT & XOR.

AND
(Act as a multiplicative operator)

OR
(Act as an additive operator)

NOT
(Act as an inverse operator)

XOR
(Functions like OR except the outputs are same)

Inputs

Output

Inputs

Output

Input

Output

Inputs

Output

0     0

0

0     0

0

0

1

0     0

0

0     1

0

0     1

1

0     1

1

1     0

0

1     0

1

1

0

1     0

1

1     1

1

1     1

1

1     1

0

 

 

AND

OR

NOT

NAND

NOR

 

XNOR

 
 

XOR

 

Gate: A device which gives the output
of any Boolean Operations when the inputs are given, called Gate.

Flip-Flops: Bistable gates/flip-flops, are
the types of circuits which is interconnected with logic gates in Integrated
Chips(IC’s). They have two states On & Off or 1 & 0; they are often
used for retrieving information. The outputs can change their states according
to rules & remains in the state until a signal is received. It’s normally
used in Electronics, Computers & Communication Technologies.

Hexa-Decimal Equivalents

23       22       21       20
(8Zeros   (4Zeros  
(2Zeros   (1Zero
&
8Ones) & 4Ones) & 2Ones) & 1One)

Hexa-Decimal Equivalent

0       0      
0       0

0

0       0      
0       1

1

0       0      
1       0

2

0       0      
1       1

3

0       1      
0       0

4

0       1      
0       1

5

0       1      
1       0

6

0       1      
1       1

7

1       0      
0       0

8

1       0      
0       1

9

1       0      
1       0

10=A

1       0      
1       1

11=B

1       1      
0       0

12=C

1       1      
0       1

13=D

1       1      
1       0

14=E

1       1      
1       1

15=F

Bit Patterns: In computers, we must deal with
0’s & 1’s; sometimes they have patterns called Bit Patterns.

            The 8-bit pattern 11100110 can be
written as E6, obtained by dividing into groups of four & changing it with
their Hexa-Decimal values.

            16-bits pattern= (1111111001110011)2=
(FE73)16.

Ø 
A
long string of bits is quite often known as “Stream”.

Main Memory: A computer device contains large number of
flip-flops; each of them has a memory of single bit. This stocker refers to
machine’s main memory. A computer’s memory is in the form of cells, each
holds eight-bit (i.e. 1Byte). A typical memory cell contains only one Byte.

Most Significant Bit (MSB)          0110110001        Least Significant Bit (LSB)

A
computer’s main memory is quite often refers to Random Access Memory (RAM).
 Every individual cell has a unique name,
known as address.

            DRAM (Dynamic RAM) or SDRAM
(Synchronous DRAM) is used in illusion to DRAM that is decreases the time
elapsed to retrieve things from memory chips.

Measuring Memory Capacity: 210=1024, it is
closed to 1000, so that’s why it is neglected as Kilo.

1KB                                         1KiloByte                                            1024Bytes

1MB                                        1MegaByte                                          1024KiloBytes

1GB                                         1GigaByte                                            1024MegaBytes

1TB                                         1TeraBytes                                          1024GigaBytes

Mass Storage: Secondary/Mass Storage devices are additional memory
devices, their different classes are:

Magnetic System:
Normally called Hard
Disk-Drive/HDD (Magnetic Disk), has a spinning disk coated with magnet is
used to store data. It is a fixed disk & having non-volatile memory
that can store & retrieve data on computer.

Optical System: It is the storage method in
which data can be hold by a reflective disk by creating marks on it. Usually a
Laser Beam is used to detect/read data by checking variations on the
spinning disk. Some examples are:

CD-
(Compact Disk)                                        600-700MB

CD-DA
(Compact Disk-Digital Audio)                        approx.
74 minute audio or beyond (decreased pitch) 

DVD
(Digital Versatile Disk)                           approx.
4.7 GB

BD
(Blu-Ray Disk)                                          Over
five times Capacity of DVD’s

Flash Drives: It is a kind of storage, unlike
the HDD or Optical Devices, it has no moving parts. Normally used to transfer
or save data from Computers, Digital Cameras etc. Some examples are:

SD                   Secure Digital

SDHC              SD- High Capacity

SDXC              SD-Extended Capacity

Representing Information in Bit Patterns: As all we know that computer
only can understand binary language in contrast to Human Language, that is why
it retrieve information/data in term of bits & our “Program” converts it
the human readable form. (Things they represent)