To help understand computers it is best to first learn about computer data. Computer data is information required by the computer to be able to operate. It is used to :
- Run programs - This is the actual executable program data that the computer will execute to run the program such as Microsoft Word.
- Store program or system configuration information.
- Store information that the computer user needs such as text files or other files that are associated with the program the computer user is running. A common example of a program the computer user is running is the Microsoft Office suite of products which include Microsoft Word, Microsoft Excel, and others. These programs are also known as applications.
Data Structure
Computer data is in what is called binary format. This means that it is always a 0 or a 1. It only has these two states and must be in one of them.
There are several fundamental data units which include:
- Bit - A data unit which must be in one of the two binary states described above. It is the smallest data unit that exists.
- Byte - 8 bits of data which has a possible value from 0 to 255.
- Word - Two bytes or 16 bits of data with a possible unsigned value from 0 to 16535.
Data transmission
Data transmission is the act of sending data from one place to another. Data is transmitted both inside and outside your computer. There are two fundamental methods of data transmission.
- Serial - Data is sent on a single line and one bit is sent at at a time. This is similar to a line which one item must come one after another.
- Parallel - Data is sent on more than one line at a time. This may be any number of bits at a time, but is usually one word at a time (two bytes) or possibly three bytes at a time.
Computer Hardware
The term computer hardware refers to the various electronic components that are required for you to use a computer along with the hardware components inside the computer case. As you know your computer equipment is made of several common components. These include:
- The main computer box.
- A monitor - Looks like a television screen.
- A keyboard.
- A mouse.
- Speakers.
- An optional printer
The main computer box is the main component of the computer. It has computer hardware parts inside that perform the following functions:
- Temporary storage of information (known as data in more technical terms) - This function is done by memory.
- Permanent storage of information - This function is done by a hard disk, floppy disk, or CD ROM.
- Manipulation or processing of data - Used to determine where data is stored and perform calculations which support operations that the user is doing.
- Interfacing to the outside components or to the outside world - This supports the ability for the user to communicate with the computer and know how the computer is responding to commands which are done primarily through the monitor, keyboard, and mouse along with their interface components in the main computer box.
- A power supply which provides the electrical power to the components in the computer box.
Software
The term software describes the programs that run on your system. This includes your computer operating system and other computer programs which run. Software is written in a computer language (such as Basic, C, Java, or others) by programmers. The computer language is in a text format and can be read by a person although if you do not understand the structure and rules of the language you may not understand it very well. Once a program is written, an operation is performed on it which is called compiling. Compiling is the process of changing the textual written language into a binary language which can be understood by the computer.
Writing these text files and converting them to computer readable files is the way operating systems and most application programs are created.
BIOS (Basic Input/Output System)
BIOS is a low level program used by your system to interface to computer devices such as your video card, keyboard, mouse, hard drive, and other devices. What BIOS programs provide in the computer are very simple function calls or small subprograms which can be used by higher level programs to perform simple operations on computer devices. For example a BIOS program would provide the ability to write a character to memory on a video card.
BIOS is normally written in a low level computer language and is permanently or semi-permanently written into the computer system. This type of computer program is commonly referred to as firmware since it was historically written permanently into computer systems. Although BIOS is a program, because of its permanent state, it was not quite considered to be software so the term firmware is used to describe it.
Historically BIOS programs were written into a type of memory called ROM (read only memory). This type of memory would not lose its data when the computer lost power thus ensuring these BIOS programs would always be available. There were different variants of ROM memory some of which could be written multiple times but this memory could not normally be changed or re-programmed once the computer system was sold to the customer. Once ROM memory was written to, it could not be written to again and could only be read when in the possession of the customer. In more recent years a more flexible form of memory was developed called flash ROM which allows ROM memory to be written to after the computer system is in possession of the customer.
