Le PowerBook G3 est un ordinateur portable d'Apple. Il fut lancé en novembre 1997, soit en même temps que les Power Macintosh G3. Bien que reprenant le même boîtier que le PowerBook 3400c, c'était une toute autre machine : il était plus rapide que le 3400c/240, déjà réputé pour sa vitesse. L'écran restait un 12,1" à matrice active pouvant afficher 800 × 600 pixels en milliers de couleurs, mais la mémoire vidéo a été étendue à 2 Mio. Le lecteur CD-ROM passait par ailleurs à 20× (contre 12× pour le 3400c), la mémoire vive à 32 Mio (contre 16 Mio), le disque dur à 5 Go (contre 2 ou 3 Go). Ces caractéristiques étaient presque identiques à celle des modèles de bureau, ce qui faisait que le PowerBook G3 rivalisait en puissance avec les tout nouveaux Power Macintosh G3 qui était déjà la nouvelle référence en termes de puissance ! Le prix de cette machine d'exception était en proportion de ses caractéristiques : environ 50 000 F TTC en France.
Il sera remplacé seulement six mois plus tard par les PowerBook Série G3 qui utilisent de nouveaux boîtiers plus fin notamment.
In computing, a keyboard is a typewriter-style device, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches. Following the decline of punch cards and paper tape, interaction via teleprinter-style keyboards became the main input device for computers.
A keyboard typically has characters engraved or printed on the keys and each press of a key typically corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or signs (characters), other keys or simultaneous key presses can produce actions or execute computer commands.
Despite the development of alternative input devices, such as the mouse, touchscreen, pen devices, character recognition and voice recognition, the keyboard remains the most commonly used and most versatile device used for direct (human) input into computers.
In normal usage, the keyboard is used to type text and numbers into a word processor, text editor or other programs. In a modern computer, the interpretation of key presses is generally left to the software. A computer keyboard distinguishes each physical key from every other and reports all key presses to the controlling software. Keyboards are also used for computer gaming, either with regular keyboards or by using keyboards with special gaming features, which can expedite frequently used keystroke combinations. A keyboard is also used to give commands to the operating system of a computer, such as Windows' Control-Alt-Delete combination, which brings up a task window or shuts down the machine. A command-line interface is a type of user interface operated entirely through a keyboard, or another device performing the function of one.