Using a computer, it is using an operating system. This definition is rather crude. What is that an operating system? We can define this term in different ways, but ultimately it is what allows a current user who doesn't understand the electronics of a computer to use: this is an interface between the hardware and the user and its software on the other hand.
This definition raises the first question, what is a computer? It is an electronic device that uses digital components to process information. The main component is the microprocessor (also called processor) that reads instructions (software programs) - suites and executes them. This is a "moron", it takes no decision, all is conditioned by these suites of instructions related to the program and conditions. Each processor family (e.g. the X 86) uses its own language and reads only the program that it can decode. In addition, a processor is linked to other related electronic components that allow it to communicate. It is here that it is complicated. Two compatible computers can use processors, motherboards, internal devices (HDD, drives / recorders, CD and DVD,...), additional cards and even external devices (printer, scanner,...) different. This part is part of the hardware 1 course.
The two other main software parts of a computer are:
The firmware is required for all systems based on microprocessors (and microcontrollers). This programming allows the processor to start the computer. In the case of the PC compatible, it is divided in 2 parts: written in memory Rom BIOS and the setup that allows to set some internal hardware configurations for the PC. Written in assembler, the internal language of the processors, the BIOS is specific to each motherboard. His decryption is almost impossible for non-specialists.
Software or programs are the only really interesting for the user. There are desktop software (Word, Excel, Access, PowerPoint,...), image processing software (Corel Draw, Adobe Photoshop,...), software management, technical drawing,...
We need to link these 2 parts, allow the user and programs installed in the computer to use electronic components such as managing files on the hard disk, the display of information... It is the role of the operating system.
A final software component based on the drivers. These are programs to use specific devices (graphics card, printer, scanner,...). They are specific to the device and operating system generally. Current operating systems include a few drivers. Without this program, you can for example not print, not his or even display limited to VGA (16 colors, 640 X 480 resolution). We'll talk about later in the course.
The first computers included the operating system directly in ROM (and therefore non-updatable). Include UNIX and some proprietary (manufacturer specific) systems in early computers. In the 1970s, the main operating system called CP/M (Control Program for Microprocessors). It was used especially for the 8-bit INTEL 8080 microprocessors.
Beginning of the 1980s, the first personal computers made their appearance. These personal computers such as the Apple II or commodore 64 used their own operating system. To facilitate their use, manufacturers usually included language basic directly in read-only memory (ROM). This interpreted language already enabled to work with the computer. Unfortunately, change computer needed to relearn the new system. Some machines of the era also use CP/M as the commodore 128 or the Amstrad (based on the Z80).
IBM, in designing its XT computer also sought an operating system. After some negotiations with Digital Research (CP/M), it asked finally to Microsoft who developed a Basic language. Based on a technology purchase, DOS is the first PC operating system compatible. Its major difference, he was included on a floppy disk and could be upgrade. It was developed until 1993 with DOS 6.22 by using an additional graphical interface (Windows 2.0, 3.0, 3.1 and 3.11).
IBM and Microsoft joined to create a more modern operating system. Finally, development will take 2 directions after separation: Microsoft's Windows NT and IBM OS2. These 2 operating systems are multi-tasking (OS2 is significantly higher for this function). Their main interest is the network manager. At the time, some networks managers were marketed as Novell Netware, an operating system wholly or even Lantastic, interfaced on DOS. After version 4.0, IBM abandoned its operating system.
The history of Microsoft operating systems splits into 2 parts, systems for personals and professionals computer.
In the range of personal, include:
In the professional range, include:
In versions network servers:
They work all with compatible PC (X 86).
Apple develops its own operating system for its computers. The latest versions of Mac OS X are based on UNIX. IOS is dedicaded to smartphone and tablets.
These are not compatible with the PC X 86 (although the latter use INTEL processors) and require that a specific interface.
Microsoft is inspired by Mac OS to create its Windows graphic interface.
For compatible PCs, there are also the LINUX family. This system is based on UNIX but repeats specific commands.
Developed in Open source, Linux is multi-user. Different commercial versions are also developed (Mandrake, Red Hart, Debian,...). The latest versions use a GUI on the text interface. Linux is seen in another course and will not be addressed here.
In the 1990s, other systems have attempted to be inserted into the PC as BeOS, an operating system developed specifically for multimedia applications. IBM with different versions of OS2 stopped any support end of 2005. They will not be seen.
Mainframe computers also use versions of UNIX, generally owners like SUN's Solaris.
Of many Tablet PCs current work on Android (a Linux derivative) or Chrome OS.