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Multimedia Hardware History

Early 1980s Generation

Many personal computers in the early 1980s could handle only text. User input was limited to typing text on keyboard and user output was limited to text display screens and text printers. The only way users could make lines and boxes was by entering peculiar text characters that included single and double lines and box corners.

Fortunately, it was pissible to upgrade many computers in this and later generations. Some upgrades take the form of optional adapter cards. Adapter cards contain additional electronic circuitry and plug into large sockets on a computer's main circuits board, which contain most of the computer's circuitry. Other upgrades are optional boxes, such as displays and printers.

Users could upgrades the early 1980s generation of computers so that software could identify, address, and change every point on a screen or on a printed page. These option allowed users to draw respectable graphics that included such as figures as diagonal lines and circles. However, because typical screen could display only two colors (black and green) or four colors, these computers could not display good colorful images.

Late 1980s Generation

The late 1980s saw many computers that could address more points on their screens and could also display 16 different colors at a time. Such computers could not only display text and graphics but could also display an acceptable image of a subject that was carefully selected to have only a limited range of colors. These computers' displays are called VGA.

Optional display adapter cards allowed users to upgrade this generation of computers to Super-VGA (SVGA), which could show 256 different colors at a time. Displaying 256 unique colors suffices for displaying quite good images, even when a subject has a wide range of colors. This generations is common in mid-1990s and allows students to create some meaningful and colorful multimedia projects.

Other optional adapter cards for the late 1980s generation of computers allowed users to add digital audio capability to a base computer. Digital audio capability mean that the computer can record and play back sounds. For example, a student can speak into a microphone. A digital audio adapter converts the microphone's output signal to the form that the computer can write onto a disk (hard disk/hard drive/fixed disk). The computers writes audio as an ordinary file, just like a file that contains a word processing document. Later, the computer can read the audio file from the disk. The adapter converts the file's information back to a signal that is suitable for playing through a speaker.

The microphone's output and the speaker's input are analog signals, whereas signals that a computer can store on its disk are digital. Converting analog audio signal to digital form and writing the digital form on a computer's disk makes it possible for students to create projects that can instantly start playing any desired audio selection.Unlike a tape recorder, a disk can find the beginning of any selection in a small fraction of a second. Thus, digital audio is what allows interactive multimedia projects to include audio as well as text, images, and graphics.

Students can use a computer that can display at least 256 colors, and can record and play digital audio, to create most multimedia projects.In fact, such computers are often called "multimedia computers," especially if computers have the additional ability to read CD-ROM (Compact Disk-Read Only Memory) discs.CD-ROM disks look exactl;y like the CD discs that replaced phonograph records. A computer can read a CD_ROM if the computer has a CD-ROM drive. Students will find that CD-ROMs are an excellent source of professionally created media. Having a CD-ROM drive is neither necessary nor sufficient for creating multimedia projects.

For creating and digitizing original media, students need access to a computer that is equipped with some additional hardware. This hardware is available as options for the late 1980s generation of computers. With additional hardware, for example, students can scan photographs into the computer that contain this additional hardware, so a less expensive setup suffices for most of the time that studentss spend creating or using a project.

Mid-1990s Generation

In the mid-1990s, many based model computers can display at least 256 colors and also have digital audio capability, either built into the computers' main circuit boards or packaged on adapter cards that come as standard parts of the base computers. These computers are also likely to come with CD-ROM drives. These affordable multimedia computers make student-created multimedia projects feasible for the first time in the mid-1990s.

As the ability to create morer sophisticated media has moved from highpriced adapter cards to reasonably priced base models, this ability has decreased significantly in price. These multimedia computers allow users to create text, graphics, images, and audio.

The mid-1990s generation is also suitable for for upgrading to handle digital video.A school that has such computers might choose to add a digital video capture adapter toone or two computers. Students can use a computer that has been upgraded with this adapter to convert moving pictures to computer files. That is, the computer can accept an analog video signal from a video camera or from a video cassete recorder (VCR), can convert the signal to digital form, and can store the resulting digital form on the computer's disk.

A computer needs a digital video capture adapter card in order to capture digital video, but a computer does not need such a card in order to play back digital video. Many students can use a single computer that has a digital video capture adapter to prepare video files and then transfer those files to the many normal computers that the student use for acttually creating projects. A local area network (LAN) makes transferring files easiest.

Analog video capability, which is an alternative to using digital video, can involve attaching a laser disk player, also known as a video disc player, to a computer. A project running on the computer controls the player by sending signals over a cable that connects the computer's serial port to a corresponding port on the player. (A serial port may be the same port to which you connect a external modem). These signal can tell the player to go rapidly to a specified place on the disc, start playing, and play video and audio until reaching another specified place on the disc. The player produces analog video and analog audio, which drive a television monitor and amplified speaker, respectively. Audia and video from a laser disc player do not actually pass through the computer and are not converted from analog to digital form. Thus, a laser disc player provides perhaps the only significant example of interactive analog audio and analog video.

The Next Generation

Playing back digital video on a slow base model computer limits the user to showing video in a small windows, that is, playing video in only small fraction of the computer's screen. A slow computer also limits the user to showing only a few pictures per second. To avoid any jerking, a computer must show 30 complete pictures (called frames) each second. This rate of 30 frames per second is called full-motion video.Television sets and analog video show full-motion video.

It is reasonable to foresee that the next generation of computers will have faster processors, faster disks, and perhaps special video playback hardware. Such computers will come closer to allowing users to show full-motion digital video on a base model computer's entire display screen.

Digital video will also benefit from future computers ability to increase the number of colors that can appear on the acreen from 256 to about 16 million. Sixteen million colors is call true-color, because it can reproduce as many more colors as a television screen can reproduce or as a human eye can distinguish.

Providing more colors will also improve future computers ability to show natural images. Next generation computers will also have sufficiently large disks to store many high-resolution images and to store long segment of digital audio and digital video. Such computer will gradually become common, thereby encouraging today's students to use full-motion, full-screen, true color digital video routinely in their adult personal and occupational communications.

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