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Computer Basics 

Introduction to computer basics 

Key Topics 

Electrical Pulses 

One’s and Zero’s 

Size definitions 

Reasons For Conversions 

Reasons For Conversions 

Working In Base 10 

Working with base 2 

Converting to Binary Example1 

Converting to Binary Example 2 

Hexadecimal Numbers 

Table of conversion 

Converting to a Hexadecimal Number 

Converting Numbers Example 2 

ASCII

Computer Basics

Introduction to computer basics

  • Computer processing is designed around binary  and we should have some familiarity with binary if we will be working computers.

  • The process for the conversion of decimal  numbers to binary  and hexadecimal  is a straightforward and practical.

Key Topics

  • Electrical pulses

  • One’s and zero’s

  • Size Definition

  • Reasons for Conversion

  • Working in base 10

  • Working in base 2

  • Converting to Binary

  • Converting to Hexadecimal

  • ASCII

Electrical Pulses

  • Since computers use electrical pulses to communicate then a pulse = yes = 1 and no pulse =No = 0.

  • Therefore computers work by using ones and zeros which is in reality using the binary  numbering system.

Ones and Zeros

  • Each one or zero defines a bit of data.

  • 8 bits of data is equivalent to one byte of data.

  • 10101101 = 1byte of data.

  • Information  is usually defined in bytes.

Size definitions

  • The quantities of space within the different devices  such as the hard drive  or the memory  are measured in proportions of bytes.

  • 8 bits = 1 byte

  • 1024 bytes = 1KB (Kilobyte)

  • 1024 KB = 1MB (Megabyte)

  • 1024 MG = 1GB (Gigabyte)

  • 1024 GB  = 1 TB (Terabyte)

  • 1024 TB = 1 EB (Exobytes)

Reasons For Conversions

  • Although binary  defines how computers work, humans work in decimal  and find it difficult to understand binary.

  • Hexadecimal numbers are used because

  • When we deal with numbers larger then 8 bits in modern computers that are 32/64 bits it becomes difficult to keep a tab on all the ones and zero’s for human beings.

  • They provide an easy conversion route to binary

Reasons For Conversions

  • You will need to be able convert  decimal  numbers into binary  and hexadecimal  and vise versa as part of your job.

  • The situations where conversion is useful include: -

  • Defining the IRQ , DMA  and IO address .

  • When dealing with TCP /IP  addresses 

  • When dealing with jumper  setting and SCSI

Working In Base 10

  • We are familiar with base 10

  • Within base 10 the largest single digit number we can have is 9

  • To calculate the value of a number

 

 

 

 

 

 

 

 

 

 

Is equivalent to: - (5x1000)+(3x100)+(2x10)+(1x8) = 5328

 

 


Working with base 2

  • Within base 2 the largest single digit number is 1

  • To calculate the decimal  value of a binary  number we look at the example below

10011000 is equivalent to: - (1x128) +(0x64) +(0x32)+(1x16)

                                    +(1x8)+(0x4)+(0x2)+(0x1)

                        = 128+16+8=152 in decimal

 

Converting to Binary Example1

  • When converting a decimal  number to binary ,

 

 

 

 

Converting to Binary Example 2

  • When converting a decimal  number to binary ,

 

Hexadecimal Numbers

Table of conversion

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Converting to a Hexadecimal Number

  • Split the binary  number in to segments with 4 digits with in it.

  • Use the conversion table to convert  each segment to its single digit hexadecimal  equivalent.

 

 

 

 

 

 

 

 

 

 


Converting Numbers Example 2

 

  • As you can see the decimal  number 210 is equivalent to 11010010 in binary , which is, intern equivalent D2 in hexadecimal

 

 

 

 

 

 

 

 


ASCII

  • ASCII stands for American Standards Code for Information  Interchange pronounced as asskee.

  • All characters on the keyboard  have been defined with individual ASCII binary  byte equivalents.

  • The character A=65 dec = 01000001 bin =41 hex

  • The character a=97 dec = 01100001 bin =61 hex

  • The character? =63 dec = 00111111 bin =3F hex

  • ASCII is a universal standard  that means that all systems recognize ASCII from PC’s to Unix  systems to Apple systems

Questions

  1. Convert the decimal  number 57 to binary

    1. 00011100

    2. 01010101

    3. 00111001

    4. 00111101

  2. Convert the decimal  number 85 to binary

    1. 00011000

    2. 01110101

    3. 10101010

    4. 01010101

    5. 00110101

  3. Convert the binary  number 11010101 to decimal

    1. 23

    2. 56

    3. 123

    4. 213

    5. 234

  4. Convert the binary  number 01110101 to decimal

    1. 223

    2. 156

    3. 117

    4. 113

    5. 234

  5. Convert the binary  number 11010101 to decimal

    1. 23

    2. 56

    3. 123

    4. 213

    5. 234

  6. Convert the binary  number 11010101 to hexadecimal

    1. AB

    2. 5C

    3. D5

    4. DF

    5. F2

  7. Convert the binary  number 11010111 to hexadecimal

    1. AB

    2. FC

    3. D5

    4. D7

    5. FF

    6. DA

 

  1. Convert the binary  number 11111111 to hexadecimal

    1. AB

    2. 5C

    3. D5

    4. DF

    5. FF

 

  1. Convert the binary  number 11111101 to hexadecimal

    1. AB

    2. 5C

    3. FD

    4. DF

    5. F2

 

  1. Convert the Decimal number 145 to hexadecimal

    1. 223

    2. 45

    3. 91

    4. 78

    5. 200

 

  1. Convert the Decimal number 192 to hexadecimal

    1. D2

    2. 45

    3. 91

    4. C0

    5. DF

 

  1. Convert the Decimal number 255 to hexadecimal

    1. BD

    2. 45

    3. 91

    4. CD

    5. FF

 

Answers to questions

1.      D

2.      D

3.      D

4.      C

5.      D

6.      C

7.      D

8.      E

9.      C

10.  C

11.  D

12.  E

 

 

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