Computer and Electronics Engineering Aspects

Types of number system:

1.       Binary number system; base ‘2’

Digits used = 0, 1 eg. (100011)₂.

2.       Octal number system; base ‘8’

Digits used = 0 to 7. eg. (352674)₈.

3.       Decimal number system; base ‘10’

Digits used = 0 to 9. eg.(86459)₁₀.

4.       Hexadecimal number system; base ‘16’.

Digits used = 0, 1, 2, 3, 4, 5, 6, 7 , 8, 9, A, B, C, D, E, F. eg.(64F32B45A)16.

Conversions with examples:

1.       Decimal to Binary:

2.       Decimal to octal:

 

-        The smallest unit of data on a binary computer is a “bit” (1 bit = 0 or 1).

-        Nibble is a collection of 4 bits.(1 nibble = 4 bits).

-        Byte consists of 8 bits. (1 Byte = 8 bits).

-        Diode can convert AC into DC but not DC into AC.

-        At absolute zero temperature semiconductor acts as an insulator.

-        Semiconductor have negative temperature coefficient of resistance.

-        When a diode is into non conducting state has a very high resistance.

-        An electrical device allowing current to move through it in one direction is called diode.

-        The term ‘diode’ is customarily used for small signal devices. I<1A.

-        The term ‘rectifier’ is used for power devices, I>1A.

-        The diode is said to be forward biased, when voltage is supplied across is diode in a way that it allows current to flow.

-        The diode is said to be reversed biased, when voltage is supplied across a diode is in a way that it prohibits the flow of current.

-        Silicon and germanium diodes have a forward voltage of approximately 0.7 and 0.3 volts.

-        Zener diodes are used as voltage regulators.

-        Photo diode is used to convert light signal into electrical signal.

-        LED converts forward current into light.

-        Varactor diodes are used in tuning a radio station, TV channel or in telecommunication, etc.

-        The bipolar junction transistors is a three layer sandwich of P-type and N-type semiconductors. The three layer may be arranged in PNP or NPN order. According to this order, there are two transistors.

PNP transistors

NPN transistors

-        An electronic/digital circuit which has one or more inputs but only one output is called logic gate.

-        A table which gives the input-output relationship of the binary variables for each gate is called truth table.

-        AND gate gives a high output(1) only if all its inputs are high. It is represented by A.B.

-        OR gate gives high output(1) if one or more of its inputs are high. Represented as A + B.

-        NOT gate is also known as an inverter.If the input variable is A, the inverted output is known as NOT gate. Written as A’ or Ᾱ.

-        EXOR (Exclusive OR) gives high output if either but not both of its to two inputs are high. It is represented as A⊕B.

Basic computer:

- Types of computer:

A.      On the basis of operation:

i.        Analog computer: Eg. Thermometer

ii.       Digital Computer: Eg. Laptop

B.      On the basis of uses:

i.        General purpose computer

ii.       Special purposes computer

C.      On the basis of capacity:

i.        Super computers

ii.       Minicomputers

iii.      Macrocomputers

-        The first electronic computer was ENIAC.

-        The first micro computer was IBM-PC.

-        The first micro processor was designed by INTEL.

-        SRAM – stands for “Static Random Access Memory.”

-        DRAM – stands for “Dynamic Random Access Memory.”

-        PROM – stands for “Progammable Read Only Memory.”

-        EPROM – Erasable Progammable Read Only Memory.

-        EEPROM – Electrically Erasable Progammable Read Only Memory.

-        Input devices : Keyboards, Mouse, Touch, Pad, Joystick, Track ball, Digital camera, etc.

-        Output devices : Monitor, Printer, Plotter, etc.

Types of operating system :

i.        Muti user : eg. MVS, UN’X

ii.       Multi programming : eg. windows 95, windows NT, UNIX,windows 3.X.

iii.      Multiprocessing : eg. MVS, UNIX.

iv.      Multithreading :

v.       Real time : eg. P-855, P-860.

-        MS-DOS doesn’t support long file names.

-        Key ingredient of processor is transistor.

-        Speed of CPU is determined by no. of transistor.

-        CRT – Cathode Ray Tube.

-        OCR – Optical Character Recognition.

-        MBR – Master Boot Record.

-        FAT – File Allocation Table.

-        FTP – File Transfer Protocol.

-        ISP – Internet Service Provider.

-        WWW – World Wide Web.

-        USP – Un-interruptible Power Supply.

-        MODEM – Modulator Demodulator.

-        VGA – Video Graphics Array.

-        E-mail messages are usually encoded in ASCII ext.

-        The capacity of a standard PC floppy is 1.4448.

-        1 KB = 1024 bits.

-        1 MB = 1024 KB.

-        1 GB = 1024 MB.

-        1 TB = 1024 GB.

-        The capacity of cache memory is 4 MB.

-        The capacity of Magnetic disk is 200 – 1000 GB.

-        TEL NET is used for remote login

-        MODEM converts digital date to analog and vice versa.

-        IP is distinct for each computer network.