What is computer memory?

Memory and Storage 

You can store data on your hard disk, while data which is being processed is stored in RAM (Random Access Memory) Data which is stored on a hard disk can be permanent, while data in RAM is only temporary. Normally when people talk about memory in relation to a PC, they are talking about RAM.

RAM

Random Access Memory (RAM) is the main 'working' memory used by the computer. When the operating

system loads from disk when you first switch on the computer, it is copied into RAM. The original IBM PC

could only use up to 640 KB of memory (just over half a megabyte), whereas a modern computer can effectively house as much RAM as the motherboard and processor support. Data and programs stored in RAM are volatile (i.e. the information is lost when you switch off the computer).

ROM‐BIOS

The 'Read Only Memory‐Basic Input Output System' chip is a chip located on the computer's system (mother) board, which contains software. This software performs a variety of tasks. When you first switch on the computer the ROM‐BIOS software performs a self‐diagnostic to check that the computer is working OK. This software then loads your operating system from the disk into the RAM.

Video (graphics) memory 

The picture which you see on your screen is a form of data and this data has to be stored somewhere. The on‐screen pictures are held in special memory chips called video memory chips; these chips are usually located on the video card. A modern motherboard is supplied with several Megabytes of video memory.

Storage capacity measurement

It is important that you understand a little about the measurements used to define storage capacities:

Bit:

Computer are digital. This means they work by processing ones and zeros. The basic one or zeros is called a bit of information.

Byte:

There are eight bits in a Byte.

KB ‐ Kilobyte:

There are approximately a thousand bytes in a KB (known as a Kilo Byte)

MB ‐ Megabyte:

There are approximately a million bytes in a MB (known as Mega Byte)

GB ‐ Gigabyte:

There are approximately a thousand, million bytes in a GB (known as Giga Byte)

TB ‐ Terabyte:

There are approximately a million, million bytes in a TB (known as Terra Byte).

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Which is better GHz or MHz?

MHz and GHz
MHz is short form Mega Hertz and GHz is short form of Giga Hertz. Hertz is usually the unit of frequency measurement. It indicates the speed of the computer’s CPU or of any other component whose performance is given in terms of frequency. Generally, higher Hertz indicates faster performance

1 MHz = 1,000,000 Hertz (1 million Hertz)
1GHz = 1,000,000,000 Hertz (1 billion Hertz)

CPU speeds

The speed (operating frequency) of the CPU is measured in megahertz (MHz) or gigahertz (GHz). The higher the value the faster the CPU will operate. The original IBM PC released way back in 1981 ran at 4.77 MHz whereas modern PCs can run at over 4000 MHz, which gives you an idea of how far things have progressed.

1 MHz means that the device will run at one million cycles per second. 1 GHz is a thousand times faster, so that 1 GHz = 1000 MHz.

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How to control computer performance

Factors those affect computer performance: 

There are a wide range of factors that can affect the performance of your computer. These include CPU speed, RAM size, type of graphics card processor and memory plus the number of applications running. It is important to realist that it is not just the speed of the CPU that affect the overall performance of your computer. There is no point in having a very fast CPU if the other parts of a computer may slow down the real world performance.

CPU speed: 
The computer speed or better say the processor speed governs how fast the CPU will run. The higher the speed the faster the computer will work for you. The speed is given in Gigahertz (GHz). The higher the GHz speed the faster the computer.

RAM size: 
Computer keeps all its working files in RAM while working. So the larger the RAM size is, the more comfortable and faster computer can perform. Like, if a person has a large table top space he will be able to work easily on many files open at a time.

Graphics card processor and memory: 
To display what user wants, computer uses its graphics card. If the graphics card memory is a little bit lower than the graphics card shares the RAM to complete its task. While a portion of the RAM is used to display things, the user is not getting the RAM at its full performance. As a result, affecting on the computer’s performance.

Number of applications running: 
Windows is a multitasking system, which means that it can run more than one program at a time. However the more programs which are running at the same time, the slower each one will run. To some extent this slowing effect depends on what each program is doing. Editing a large high definition video for instance can

take up a lot of CPU time. 

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What are the important parts of the computer?

Parts of a computer: You should understand some of the basic elements that make up a computer including:
‐ Central processing unit (CPU)
‐ Types of memory
‐ The hard disk
‐ Input and output devices

CPU: 
The CPU (Central Processing Unit) is normally an Intel (or equivalent) and it is one of the most important components within your computer. It determines how fast your computer will run and the CPU speed is measured by its MHz or GHz speed. Thus, a 2 GHz Pentium is much faster than say a 1 GHz Pentium CPU. It

is the CPU which performs all the calculations within the computer, when running programs such as word-processors, spreadsheets and databases. The CPU contains following elements. 

Control Unit: The control unit is responsible for controlling the sequencing and timing of the other elements making up
the CPU.

Arithmetic Logic Unit (ALU): The ALU performs the mathematical calculations using data stored within the CPU registers.

Registers: The registers are memory storage areas within the CPU that hold the data that is worked on by the ALU.

BUS: The computer bus transports data between the memory and registers.

Memory (RAM): 
The RAM (Random Access Memory) within your computer is where the operating system is loaded to when you switch on your
computer and also where your applications are copied to when you
start an application, such as a word processor or database program.
When you create data, (e.g. letters and pictures), these are initially
created and held in RAM and then copied to disk when you save the data. As a rule of thumb, the more RAM you have installed in your computer the better. These days you will commonly find over 512 Megabytes of RAM installed.

ROM‐BIOS: 
The ROM‐BIOS (Read Only Memory ‐ Basic Input Output System) chip is a special chip held on your computer's system (mother) board. It contains software which is required to make your computer work with your operating system, for instance it is responsible for copying your operating system into RAM when

you switch on your computer.

Disks: 
You use disks to store any data that you create. This can range from a memo created within a word processor to a video file created using a video camera. There are many different types of disk.

The Hard (Fixed) Disk:  Hard disks are the main, large data storage areas within your computer. Hard disks are used to store your operating system, your application programs (i.e. your word
processor, games etc) and your data. They are much faster than CD/DVDs and can also hold much more data. Hard disks are installed within the system unit of your computer.

Input/output ports:  The Input and Output ports are normally located at the back or on the side of your computer. These
include ports such as USB, serial, parallel, network and FireWire ports. You plug cables into these ports to connect your computer to other devices, such as printers, scanners and cameras.

Universal Serial Bus (USB) Port: 
The Universal Serial Bus is a relatively new item within the PC. You will see one or more USB sockets at the back of the system unit, allowing you to plug in devices designed for the USB. These devices include printers, scanners and digital cameras. Memory sticks can also be plugged into a USB port allowing you to copy data to or from your hard disk.

Serial Port:  The serial port is a socket located at the back of your computer which enables you to connect items to the computer, such as a modem. They are commonly labelled as COM1 or COM2.

Parallel Port:  The parallel port is a socket located at the back of your computer which enables you to connect items to the computer, such as a printer. It is commonly labelled as LPT1 or LPT2.

NOTE: The parallel port used to be the main way the computer connected to a printer. These days you are more likely to use a USB cable to connect the computer to a printer.

Network Port: 

The network port allows you to plug a ‘network cable’ into your computer, which then lets you communicate with other computers connected to your local network or to other computers via the Internet.




FireWire Port:  FireWire is an interface from Apple Inc. that allows high data transfer between your computer and a compatible device such as a digital camera. FireWire has largely replaced earlier ways of transferring data, such as parallel or SCSI cables. There are numerous versions of FireWire including fibre optic, coaxial and wireless versions. Most multimedia computers will have FireWire ports built into them. Firewire connectors usually look like this. 

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Common handheld portable digital devices | Personal Digital Assistant (PDA)

Personal Digital Assistant (PDA)  These devices use a special pen, rather than a keyboard and can be used for storing and retrieving information. Like most computer devices, many can connect to the Internet. They are extremely compact. PDAs have many built‐in features such as a calculator, a clock and a calendar. Many allow you to send and receive emails and even browse the web.

PDAs can also be used for accessing the Internet, sending and receiving e‐mails, video recording, typewriting and word processing, use as an address book, making and writing on spreadsheets, scanning bar codes, playing computer games, recording survey responses, and Global Positioning System (GPS).

Newer PDAs also have both colour screens and audio capabilities, enabling them to be used as mobile phones (smartphones), web browsers, or portable media players. Many PDAs can access the Internet, intranets or extranets via Wi‐Fi, or Wireless Wide‐Area Networks (WWANs). Many PDAs employ touch screen technology.

Capacity: Much smaller storage capacity compared to a PC.
Speed: Much less than a PC unless you pay a lot extra.
Costs: In relative terms expensive when compared to a PC.
Typical Users: Mostly business users.

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Laptop/Notebook & Tablet PC

Laptop computers, as the name implies, are small portable computers which can run on batteries as well as mains power. They use special screens, rather than the traditional bulky monitors, which allows for longer battery life as well as portability. A newer term, “Notebooks”, simply indicates a VERY small laptop. These are especially popular with salespersons on the move or people giving presentations. While they tend to still be more expensive than an equivalent Desktop computer, they can now match the power of a Desktop computer. Palmtops are even smaller computers which can literally fit into the palm of your hand. 

Capacity: Large hard disks combined with a
large working memory (RAM) – Often less powerful than for a PC of equivalent price.

Speed: Fast. Normally measured in GHz. Often speed specifications are less than for a PC of equivalent price.

Costs: Components need to be much more compact, so there is a price overhead when compared to a PC of equivalent power.


Typical Users: Business users, people on the move, educational users.

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What is Apple computers ?

The Apple Mac is a PC. It uses a different operating system, and may require special versions of application programs (such as word processors or spreadsheets). Even the hardware add‐ons have to be customized to some extent to be able to be connected to a Mac In the early days the thing which really distinguished the Mac over the IBM PC was the GUI (Graphical User Interface), or in plain English the way you could use the mouse to drive the computer. In the early days of the PC, you really had to be a bit of an expert to use and maintain your PC. Recently the differences between the IBM PC and the Mac have blurred, with Microsoft buying a stake in Apple. 

 

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