Characteristic of Algorithm

Characteristic of Algorithm: 

1. It must be finite
2. It must be unambiguous
3. It must have zero or more inputs
4. It must have one or more outputs
5. It must be executable

What is an algorithm?

Algorithm: 

An algorithm is the sequence of steps taken to solve a problem.
An algorithm is a procedure or formula for solving a problem, based on conducting a sequence of specified actions. A computer program can be viewed as an elaborate algorithm. In mathematics and computer science, an algorithm usually means a small procedure that solves a recurrent problem.

Program Development Steps

Program Development Steps:

A computer is a set of formal instructions, which the computer executes in order to carry out some designated task. There are six basic steps in the development of a program: 

1. Define the Problem: This step involves the careful reading and re-reading of the problem until the programmer understands completely what is required.
2. Analysis: Once the problem has been defined, the programmer may decide to break the problem up into smaller tasks or steps, and several solutions me be considered. The solution outline often takes the shape of a hierarchy or structure chart.
3. Design: Using the solution outline developed in step 2, the programmer then expends this into an algorithm that describe exactly the tasks to be performed and the order in which they are to be carried out.

Virtual Memory

Virtual Memory: 

The portion of secondary memory that execution of a program is called virtual memory.
If space needed for the program a portion of secondary memory automatically converted as a primary memory and it get backs to the secondary memory as soon as the execution of the program is finished. This is how a virtual memory works. So, this can say, virtual memory is technique for storing program or data in a secondary memory and making them appear to be in primary memory by swapping pages of segment in and out of primary memory when needed.

Cache Memory

Cache Memory: 

Cache memory is extremely fast memory that is built into a computer’s CPU or located next to in on a separate chip. The CPU uses cache memory to store instructions that are repeatedly required to run programs, improving overall system speed. The advantage of cache memory is that the CPU does not have to use the motherboard’s system bus for data transfer. Whenever data must be passed through the system bus the transfer speed slows to the motherboard’s capability. The CPU can process data much faster by avoiding the bottleneck created by the system bus.

Difference between EPROM and EEPROM

EPROM vs. EEPROM:

EPROM		EEPROM
EPROM stands for erasable programmable read only memory	1		EEPROM stands for electrically erasable programmable read only memory
Stored data can be erased by using ultra violet ray	2		Its data erased with higher voltages/ electrical signal.
All data stored in EPROM are erased when the user erased data	3		The case of EEPROM one can erase data of a fixed memory cell
The speed of EPROM which data can be read within 45 nsec to 90 nsec	4		The speed of EEPROM at which data can be read within 45 nsec to 200 nsec

Difference between Static RAM and Dynamic RAM

Static RAM vs. Dynamic RAM:

Static RAM		Dynamic RAM
Information stored on RS flip-flops	1		Information stored on FET transistors
No needs to be refreshed	2		Needs to be refreshed
Capacity is low	3		Capacity is high
It is expensive	4		It is cheap in cost
Much faster	5		Slower than static RAM

Difference between RAM and ROM

RAM Vs. ROM:

RAM		ROM
RAM is volatile	1		ROM is non-volatile
High speed	2		Access speed is less
Small in size	3		Larger size
Read/ write memory	4		Read only memory
Continuously power supply is needed for RAM to maintain its state	5		ROM does not need such continuous power supply

Different types of ROM: MROM, PROM, EPROM, EEPROM

Different types of ROM: 

Primary memory is the main area in a computer in which data is stored for quick access by the computer’s processor.
ROM (Read Only Memory) is a type of primary memory. It is a non-volatile memory chip, in which data is stored permanently and cannot be altered by the programmer. The data stored in a ROM chip can only be read and used-they cannot be changed. This is the reason why it is called read only memory (ROM).
There are four types of ROM:

1. MROM (mask ROM)
2. PROM (programmable ROM)
3. EPROM (erasable programmable ROM)
4. EEPROM (electrically erasable programmable ROM)

MROM: 

MROM (mask ROM) is manufacturer-Programmed ROM in which data is burnt in by the manufacturer of the electronic equipment in which it is used and it is not possible for a user to modify programs or data stored inside the ROM chip.

PROM: 

PROM (programmable ROM) is one in which the user can load and store “read-only” programs and data. In PROM the programs or data are stored only fast time and the stored data cannot modify the user.

EPROM: 

EPROM (erasable programmable ROM) is one in which is possible to erase information stored in an EPROM chip and the chip can be reprogrammed to store new information. When an EPROM is in use, information stored in it can only be “read” and the information remains in the chip until it is erased.

EEPROM:

 EEPROM (electrically erasable programmable ROM) is one type of EPROM in which the stored information is erased by using high voltage electric pulse. It is easier to alter information stored in an EEPROM chip.

Different types of RAM: Static RAM, Dynamic RAM

Different types of RAM: 

Primary memory is the main area in a computer in which data is stored for quick access by the computer’s processor.
RAM (Random Access Memory) is a type of primary memory. It accessed any piece of data at any time, RAMs stores data as long as the computer is switched on or is in use. RAM is volatile.
There are two types of RAM. They are:

1. Static RAM
2. Dynamic RAM

• Static RAM: 

This type of RAM is static in nature, as it does not have to be refreshed at regular intervals. Static RAM is made of large number of flip-flops on IC. It is being costlier and having packing density.

• Dynamic RAM: 

This type of RAM holds each bit of data in an individual capacitor in an integrated circuit. It is dynamic in the sense that the capacitor charge is repeatedly refreshed to ensure the data remains intact.

Difference between Primary Memory and Secondary Memory

Primary Memory vs. Secondary Memory:

Primary Memory		Secondary Memory
It is volatile	1		It is non-volatile
Directly access by the processor.	2		Not directly access by the processor.
Much faster.	3		Slower than primary memory.
It is expensive.	4		It is cheap in cost.
Low capacity.	5		Large capacity.
Example: RAM, ROM	6		Example: Hard disk, floppy disk.

Feature/ characteristics of Secondary Memory

Feature/ characteristics of Secondary Memory:

1. It is non-volatile.
2. It cannot directly access by the computer processor.
3. It is slower than primary memory.
4. It is cheap in cast.
5. It has large capacity.
6. Example: Hard disk, Floppy disk etc.

Feature/ characteristics of Primary Memory

Feature/ characteristics of Primary Memory:

1. It is volatile
2. Directly access by toe computer processor.
3. Primary memory is much faster.
4. It is more cost effective or expensive.
5. Its capacity is low.
6. Example: RAM, ROM

Read Only Memory (ROM)

Read Only Memory (ROM):

The ROM is nonvolatile memory. It retains stored data and information if the power is turned off. In ROM, data are stored permanently and can’t alter by the programmer.
There are four types of ROM:

1. MROM (mask ROM)
2. PROM (programmable ROM)
3. EPROM (erasable programmable ROM)
4. EEPROM (electronically erasable and programmable ROM)

Random Access Memory (RAM)

Random Access Memory (RAM): 

RAM is a type of computer primary memory. It accessed any piece of data at any time. RAM stores data for as long as the computer is switched on or is in use. This type of memory is volatile.

Figure: RAM (Random Access Memory)

The two types of RAM are:

1. Static RAM
2. Dynamic RAM

Classification of computer memory: Primary Memory & Secondary Memory

Classification of computer memory: 

The instructions and data are stored in memory unit of the computer system are divided into following main groups:

1. Main or Primary memory,
2. Secondary memory.

Primary Memory: 

Primary memory is the main area in a computer in which data is stored for quick access by the computer’s processor. 

Primary memory is divided into two parts.

• RAM (random access memory)
• ROM (read only memory)

Secondary Memory: 

Secondary memory is where programs and data are kept on a long time basis. It is cheaper from of memory and slower than main or primary memory. It is non-volatile and cannot access data directly by the computer processor. It is the external memory of the computer system. 

Example: hard disk drive, floppy disk, optical disk/ CD-ROM.

Figure: Classification of computer memory

Memory

Memory: 

Memory involves the process of acquiring storing and recalling data and information.
The computer memory is the electronic holding place for storing and recalling all the instructions and data that the computer can reach quickly.

Figure: Memory

Difference between Multi-programming OS and Time sharing OS

Multi-programming OS vs. Time sharing OS:

Multi-programming OS		Time sharing OS
The process can be executed by a single processor	1		In this process two or more users can uses a processor on their own terminal
It has no fixed time slice	2		It has fixed time slice
In case of multi-programming before finishing a task the execution power is not taken off	3		The execution power is taken off before finishing of execution
Example: Mac OS	4		Example: Windows NT

Difference between Batch Processing OS and Multi-programming OS

Batch Processing OS Vs. Multi-programming OS:

Batch Processing OS		Multi-programming OS
It is slower in processing	1		It is faster in processing
CPU needs to stand idly in this process	2		CPU needs not stand idly in this process
The processes have to wait in a queue	3		No process has to wait in a queue
The execution of process starts batch wise	4		The execution of process starts as it centers the processor

Difference between Multi-programming OS and Multiprocessing OS

Multi-programming OS Vs. multiprocessing OS:

Multi-programming OS		Multiprocessing
This process can be executed by a single process.	1		This process can be executed by two or more processor.
User doesn’t have to wait to end the program.	2		Many programs can be processed separately.
Process over lapping occurs here.	3		Process over lapping doesn’t occur here.
The whole system stops if the CPU is damaged.	4		The system runs smoothly even often the damage of one or more CPU.