| It has been less than 30 years since the computer | | | | commands using obscure words and abbreviations. |
| became personal, but in that time it has undergone | | | | Further, each program that wanted to use a printer |
| several major transformations as well continual | | | | or other attached device had to include code that |
| evolution. Now personal computing is poised once | | | | could control the specific brand and model of device |
| again on the threshold of a major transformation that | | | | the user happened to have. These limitations created |
| will alter the way we use them. As with each prior | | | | some problems for users as well as application |
| transformation, the result will be easier, faster, and | | | | software developers, but the overall improvement in |
| more reliable operation better tuned to the needs of | | | | PC usability was substantial. |
| the user. | | | | Graphical Command Appears |
| The earliest versions of what became personal | | | | The next transformation of the PC addressed those |
| computers appeared in the early '70s. These systems | | | | early OS limitations by changing the OS from a |
| targeted electronic hobbyists, however, not the | | | | "command line" interface into a graphical interface |
| general public. They were electronic boards without | | | | that used pictures instead of words and mouse clicks |
| enclosure, keyboard, or screens; only a calculator | | | | instead of typing. The Apple and Microsoft DOS |
| keypad and some numeric displays. No software was | | | | operating systems became the MacOS and Windows. |
| available for them. They needed to be programmed | | | | Users now could control their computers easily and |
| one instruction at time using arcane numeric codes | | | | intuitively through the "point-and-click" approach |
| and could only do very simple things. | | | | rather than by typing in computer language. Along the |
| The first transformation came in the mid-70s when | | | | way the OS created standardized ways of handling |
| companies such as Apple and IBM began offering | | | | attached devices so that there was no longer a need |
| systems for use by the general public. These were | | | | to worry about an application having the right code |
| the first true personal computers (PC) and came in a | | | | for using a specific model of device. |
| form that is still recognizable as a PC today. The | | | | The OS has undergone substantial evolution since |
| electronics were fully enclosed and they had full | | | | then. Windows, for instance, went through Windows |
| keyboards attached or built-in. They used attached | | | | 3.1, Windows 95, Windows 98, Windows ME, |
| monitors (sometimes even televisions) as displays. | | | | Windows XP, and now Vista. At each stage the OS |
| More importantly, users could load fully-developed | | | | added more code to simplify the user's task, added |
| software programs and run them on these PCs. This | | | | applications code for functions such as e-mail and |
| turned what was an expensive toy to a device that | | | | web browsing, and generally became more complex. |
| could perform a useful function. | | | | Today's PCs thus offer an astounding array of built-in |
| One of the keys to this transformation was the | | | | capabilities even before a user adds applications |
| incorporation of a special program built directly into | | | | programs such as games and word processors to |
| the PC. This program (software) was stored in an | | | | their PC's repertoire. |
| integrated circuit chip (hardware) and thus came to | | | | Unfortunately this has come with increasing cost. The |
| be called "firmware." The PC began executing this | | | | boot process, once only a few seconds long, can |
| firmware as soon as the on-off switch was thrown. | | | | take many minutes to load all of the OS and its |
| The program's function was to prepare the computer | | | | built-in applications. The memory and disk space |
| for operation, to read what users typed on the | | | | needed to store and then to run this software has |
| keyboard, to display things on the monitor, and give | | | | increased dramatically. The many different pieces of |
| the computer an ability to accept new programs for | | | | code running concurrently just within the operating |
| execution on demand. The firmware, developed by | | | | system have slowed down the computer's |
| companies such as Phoenix Technologies, was called | | | | responsiveness and each application program added |
| the Basic Input-Output System (BIOS) and formed | | | | to the menu compounds the problem. As a result the |
| the foundation upon which all further programming of | | | | PC has become costly and sluggish and offers many |
| the PC was built. | | | | more functions that most users will ever need. Also, |
| Rise of the OS | | | | this immense complexity has increased the likelihood |
| These early PCs used cassette tapes to hold the | | | | that something will go wrong, preventing the |
| user's software programs and could only load and | | | | computer from continuing to execute code - |
| execute one program at a time. An alternative | | | | "crashing" - until it is turned off and re-started. |
| quickly arose, however, replacing the magnetic tape | | | | The stage is set for another transformation in the PC |
| in the cassette with a flexible magnetic disk in a | | | | that will address these issues. The BIOS firmware |
| flexible housing - the floppy disk. Along with the | | | | that serves as the foundation for this OS and |
| advent of the floppy disk came the second | | | | application software tower is about to undergo a |
| transformation of the PC - the development of an | | | | fundamental change. Rather than loading the OS and |
| operating system. | | | | transferring computer control to that program, the |
| An operating system (OS) is a program that tells the | | | | foundation firmware will retain control. Using a |
| computer how to handle the loading and execution of | | | | software technique called "virtualization," this |
| other programs as well as how to manage resources | | | | foundation firmware (no longer just a BIOS) will allow |
| such as memory, input and output (I/O) channels, | | | | the OS to execute as though it had control while |
| attached peripheral devices, and the like. One key | | | | maintaining its own operation independent of the OS. |
| feature of an OS is that it allows the computer to | | | | In effect, the firmware splits the computer into the |
| execute several programs concurrently. So, a | | | | real machine, which it controls, and a virtual machine |
| program that sends information out to a printer can | | | | that executes the OS and all user applications. |
| be running at the same time as one that balances a | | | | Virtualization: The Next Stage |
| checkbook. This ability to do many things at the | | | | This virtualization has several benefits. For one, it |
| same time made the personal computer even more | | | | ensures that an error in the OS or application |
| powerful. | | | | software does not halt the computer's operation. |
| The computer now had a multi-stage start-up | | | | The foundation firmware will continue to operate |
| sequence. Turning on power caused the computer to | | | | even if the virtual computer crashes. This greatly |
| run the BIOS program, which in turn loaded the OS | | | | simplifies recovery from errors without requiring |
| off of disk and ran it. The OS then allowed the user | | | | re-boot of the computer. |
| to load and run application programs off of disk. | | | | Another benefit is that the firmware can prevent |
| Engineers compared the operation to pulling oneself | | | | malicious software such as viruses from taking |
| up by ones bootstraps, and the term "boot" became | | | | control of the computer. The firmware resides in a |
| the name of the whole sequence. Along the way | | | | chip and cannot be altered by anything the computer |
| floppy disks became more compact and developed a | | | | does. Thus, no program that sneaks onto the |
| hard shell (although the disk inside was still flexible), | | | | computer can corrupt or compromise the firmware's |
| then were supplanted by built-in hard disk drives that | | | | operation. |
| could hold both the OS and hundreds of application | | | | The foundation firmware can also incorporate key |
| programs. | | | | application programs. Their location within the |
| Several different operating systems arose but only | | | | foundation means that they enjoy its protection, so |
| two survived in the market. One was the operating | | | | no viruses or programming errors can damage or |
| system used in Apple computers. The other was | | | | hijack them. The location also ensures that they are |
| Microsoft's Disk Operating System - MS-DOS - also | | | | available for use as soon as the computer receives |
| simply called DOS, used in the IBM PCs. Over time | | | | power. They do not need for the OS to finish |
| the IBM type of PC came to dominate the market, | | | | booting up to become active. This means that users |
| representing some 90% of all personal computers | | | | can access these programs instantly, without waiting. |
| sold. For many, the term PC means an IBM-type | | | | It will also be possible to create computers that use |
| computer. | | | | only this foundation firmware without any other OS, |
| These early operating systems required users to tell | | | | opening the opportunity for an extremely compact, |
| the computer what they wanted to do and which of | | | | lightweight, and inexpensive PC with a simplified set |
| many available programs on disk to run by typing in | | | | of applications. |