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47-694: The unit has a membrane keyboard and 2 KB of RAM internally and 0.5 KB of color RAM (1024 × 4 bits). It uses a television set for a display. It uses the same chipset and 6510 CPU as the Commodore 64, the same SID sound chip, and a MOS Technology 6566 graphics chip, a version of the VIC-II that powers the C-64 graphics for the MAX' static RAM . A tape drive could be connected for storage, but each cartridge had to implement its own cassette driver and protocol routines, so

94-409: A printed circuit board (PCB) and covered by a thin, insulating film of soldermask which acts as a dielectric . For the most common, foam and foil implementation of this technology, the movable part ends with a flat foam element about the size of an aspirin tablet , finished with aluminum foil. Opposite the switch is a PCB with the capacitor pads. When the key is pressed, the foil tightly clings to

141-407: A touchscreen interface, have no physical switches and provide artificial audio and haptic feedback instead. This variety of keyboard can prove useful, as it is not limited by the rigid nature of physical computer keyboards. The majority of modern keyboards include a control processor and indicator lights to provide feedback to the user (and to the central processor ) about what state the keyboard

188-499: A beep or flash of light on actuation. Although this keyboard design was commonly used in the early days of the personal computer (on the Sinclair ZX80 , ZX81 , and Atari 400 ), they have been supplanted by more responsive and modern designs. Computer keyboards made of flexible silicone or polyurethane materials can roll up in a bundle. This type of keyboard can take advantage of the thin flexible plastic membranes, but still pose

235-430: A buckling spring over a capacitive PCB, similar to the later Model M keyboard, but instead used membrane sensing in place of a PCB. The Topre Corporation design for switches uses a conical spring below a rubber dome. The dome provides resistance, while the spring does the capacitive action. Hall effect keyboards use Hall effect sensors to detect the movement of a magnet by the potential difference in voltage. When

282-425: A diode between each intersection, allowing the keyboard microcontroller to accurately sense any number of simultaneous keys being pressed, without generating erroneous ghost keys. Optical character recognition (OCR) is preferable to rekeying for converting existing text that is already written down but not in machine-readable format (for example, a Linotype -composed book from the 1940s). In other words, to convert

329-403: A few game ports of popular arcade games. This microcomputer - or microprocessor -related article is a stub . You can help Misplaced Pages by expanding it . Membrane keyboard A membrane keyboard is a computer keyboard whose keys are not separate, moving parts , as with the majority of other keyboards, but rather are pressure pads that have only outlines and symbols printed on

376-477: A flat, flexible surface. Very little tactile feedback is felt when using such a keyboard. Membrane keyboards work by electrical contact between the keyboard surface and the underlying circuits when keytop areas are pressed. These models were used with some early 1980s home computers which lead to greater adoption of the design. The keyboards are inexpensive to produce, and are more resistant against dirt and liquids than some other keyboard types. However, due to

423-509: A horizontal beam). The mechanism of the optical keyboard is very simple – a light beam is sent from the emitter to the receiving sensor, and the actuated key blocks, reflects , refracts or otherwise interacts with the beam, resulting in an identified key. A major advantage of optical switch technology is that it is very resistant to moisture, dust, and debris because there are no metal contacts that can corrode. The specialist DataHand keyboard uses optical technology to sense keypresses with

470-482: A key is depressed, it moves a magnet that is detected by a solid-state sensor. Because they require no physical contact for actuation, Hall-effect keyboards are extremely reliable and can accept millions of keystrokes before failing. They are used for ultra-high reliability applications such as nuclear power plants, aircraft cockpits, and critical industrial environments. They can easily be made totally waterproof, and can resist large amounts of dust and contaminants. Because

517-453: A key is pressed, it oscillates ( bounces ) against its contacts several times before settling. When released, it oscillates again until it comes to rest. Although it happens on a scale too small to be visible to the naked eye, it can be enough to register multiple keystrokes. To resolve this, the processor in a keyboard debounces the keystrokes, by averaging the signal over time to produce one "confirmed" keystroke that (usually) corresponds to

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564-764: A low or non-existent tactile feedback, some people have reported difficulty typing with them, especially when larger numbers of characters are being typed. Chiclet keyboards are a variation of the design. Aside from early hobbyist/kit/home computers and some video game consoles , membrane-based QWERTY keyboards are used in some industrial computer systems, and are also found as portable, even "rollable-collapsible" designs for PDAs and other pocket computing devices. Smaller, specialized membrane keyboards, typically numeric-and-a-few-control-keys only, have been used in access control systems (for buildings and restricted areas), simple handheld calculators, domestic remote control keypads, microwave ovens, and other similar devices where

611-403: A magnet and sensor are required for each key, as well as custom control electronics, they are expensive to manufacture. A hall switch works through magnetic fields. Every switch has a small magnet fixed inside it. When the electricity passes through the main circuit, it creates a magnetic flux. Every time a key is pressed, the magnetic intensity changes. This change is noticed by the circuit and

658-502: A metal leaf, where the movable contact is a leaf spring. A major producer of discrete metal contact switches is Cherry , who has manufactured the Cherry MX family of switches since the 1980s. Cherry's color-coding system of categorizing switches has been imitated by other switch manufacturers, such as Gateron and Kailh among many others. Keyboards which utilize this technology are commonly referred to as "mechanical keyboards", but there

705-680: A simple, easily replaceable protective clear sheet can be placed in front of the membrane. Membrane keyboards are widely used in consumer electronics, industrial, commercial, scientific and military equipment. Keyboard technology#Rubber dome over membrane The technology of computer keyboards includes many elements. Many different keyboard technologies have been developed for consumer demands and optimized for industrial applications. The standard full-size (100%) computer alphanumeric keyboard typically uses 101 to 105 keys; keyboards integrated in laptop computers are typically less comprehensive. Virtual keyboards , which are mostly accessed via

752-537: A single light beam and sensor per key. The keys are held in their rest position by magnets ; when the magnetic force is overcome to press a key, the optical path is unblocked and the keypress is registered. A laser projection device approximately the size of a computer mouse projects the outline of keyboard keys onto a flat surface, such as a table or desk. This type of keyboard is portable enough to be easily used with PDAs and cellphones, and many models have retractable cords and wireless capabilities. However, this design

799-615: A single press or release. Early membrane keyboards had limited typing speed because they had to do significant debouncing. This was a noticeable problem on the ZX81 . Keycaps are used on full-travel keyboards. While modern keycaps are typically surface-printed, they can also be double-shot molded , laser marked , dye sublimation printed , engraved , or made of transparent material with printed paper inserts. There are also keycaps which utilize thin shells that are placed over key bases, which were used on several IBM PC keyboards. Switches allow for

846-411: A spring, and a slider, and sometimes other parts such as a separate tactile leaf or clickbar. At rest, the metal contacts inside of the switch are held apart. As the switch is pressed down, the contacts are held together to conduct current for actuation. Many switch designs use gold for contact material to prolong the lifetime of the switch by preventing switch failure from oxidization. Most designs use

893-419: Is a "spacer" containing holes wherever a two conductive "key" pads count touch upon being pressed. The third layer keeps the other two layers separated in order to prevent short-circuit . Under normal conditions, the switch (key) is open, because current cannot cross the non-conductive gap between the traces on the bottom layer. However, when the top layer is pressed down (with a finger), it makes contact with

940-552: Is desirable. They can have non-tactile, polydome tactile and metal dome tactile keys. Polydome tactile membrane switches use polyester, or PET, and is formed to create a stiff plastic dome. When the stiff polydome is pressed, the conductive ink on the back of the polydome connects with the bottom layer of the circuit. Metal dome membrane switches are made of stainless steel and offer enhanced durability and reliability and can feature custom dome designs. Non-tactile flat-panel membrane keyboards have little to no keypress feel and often issue

987-486: Is in. Plug-and-play technology means that its "out of the box" layout can be notified to the system, making the keyboard immediately ready to use without the need for further configuration, unless the user so desires. This also enables manufacture of generic keyboards for a variety of language markets, that differ only in the symbols engraved on the keytops. A common membrane design consists of three layers. The top and bottom layer have exposed electrical matrix traces, and

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1034-472: Is loaded from plug-in cartridges - turning on the MAX with no cartridge inserted yielded only a blank screen. Its ROM cartridge architecture was compatible with that of the C-64, so that MAX cartridges will work in the C-64. The MAX compatibility mode in C-64 was later frequently used for "freezer" cartridges (such as the Action Replay ), as a convenient way to take control of the currently running program. It

1081-455: Is no debouncing necessary. The sensor tells enough about the distance of the keypress to allow the user to adjust the actuation point (key sensitivity). This adjustment can be done with the help of the bundled software and individually for each key, if so implemented. A keyboard which utilizes these abilities include the Realforce RGB . IBM 's Model F keyboard is a design consisting of

1128-404: Is not a universally agreed-upon clear-cut definition for this term. Hot-swappable keyboards are keyboards in which switches can be pulled out and replaced without requiring the typical solder connection. Instead of the switch pins being directly soldered to the keyboard's PCB , hot-swap sockets are instead soldered on. Hot-swap sockets can allow users to change different switches out of

1175-443: Is prone to error, as accidental disruption of the laser will generate unwanted keystrokes. This type of keyboard's inherent lack of tactile feedback makes it often undesirable. The buckling spring mechanism (expired U.S. patent 4,118,611 ) atop the switch is responsible for the clicky response of the keyboard. This mechanism controls a small hammer that strikes a capacitive or membrane switch. IBM 's Model F keyboard series

1222-408: Is the scissor-switch, based on the scissors mechanism . Due to the requirement of many notebooks to be slim, they require the keyboards to be low-profile. Therefore, this technology is most commonly featured on notebooks. The keys are attached to the keyboard via two plastic pieces that interlock in a "scissor"-like fashion and snap to the keyboard and the keycap. These keyboards are generally quiet and

1269-485: The shift , alt and control state of the keyboard. The keyboard switch matrix is often drawn with horizontal wires and vertical wires in a grid which is called a matrix circuit . It has a switch at some or all intersections, much like a multiplexed display . Almost all keyboards have only the switch (but no diode) at each intersection, which causes "ghost keys" and "key jamming" when multiple keys are pressed ( rollover ). Certain, often more expensive, keyboards have

1316-577: The Max as a video game console rather than a home computer, despite sharing much of the Commodore 64's chipset. The MAX's 2KB of RAM also indicates it was intended as a games machine and not a personal computer. Even the Commodore PET , released five years earlier in 1977, had a minimum of 4K RAM, and rapidly 8K became the minimum. Even the VIC-20, heavily criticized for its minimal RAM, shipped with 5K of RAM. Software

1363-404: The amount of typing is relatively small or infrequent, such as cell phones. Modern PC keyboards are essentially a membrane keyboard mechanism covered with an array of dome switches which give positive tactile feedback. The membrane (typically made out of Polyethylene terephthalate or PET) keyboard consists of three layers: two layers containing traces of conductive ink and the center layer

1410-456: The bottom layer. The conductive traces on the underside of the top layer can then bridge the gap, allowing current to flow. The switch is now "closed", and the parent device registers a keypress. Many applications benefit from the sealed nature of the membrane keypad. Feedback can easily be provided to the user via audible means (e.g. a beep) or visually (lights or via the display itself), or via both means together. For additional wear resistance,

1457-407: The illumination of the " caps lock ", " num lock " and " scroll lock " lights. A common test for whether the computer has crashed is pressing the "caps lock" key. The keyboard sends the key code to the keyboard driver running in the main computer; if the main computer is operating, it commands the light to turn on. All the other indicator lights work in a similar way. The keyboard driver also tracks

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1504-419: The keyboard is in. Depending on the sophistication of the controller's programming, the keyboard may also offer other special features. The processor is usually a single chip 8048 microcontroller variant. The keyboard switch matrix is wired to its inputs and it processes the incoming keystrokes and sends the results down a serial cable (the keyboard cord) to a receiver in the main computer box. It also controls

1551-447: The keyboard without having the tools or knowledge required to solder. The reed module in a reed switch consists of two metal contacts inside of a glass bubble usually sealed with some inert gas like nitrogen to help prevent particle build-up. The slider in the housing pushes a magnet down in front of the reed capsule and the magnetic field causes the reed contacts to become attracted to each other and make contact. The reed switch mechanism

1598-516: The keys require little force to press. Scissor-switch keyboards are typically slightly more expensive. They are harder to clean (due to the limited movement of the keys and their multiple attachment points) but also less likely to get debris in them as the gaps between the keys are often smaller (as there is no need for extra room to allow for the 'wiggle' in the key, as typically found on a membrane keyboard). Flat-panel membrane keyboards are often used in harsh environments where water or leak-proofing

1645-542: The middle layer is a spacer to prevent current from passing through the top and bottom conductive traces passively. When pressure is applied to the top membrane, it bridges the top and bottom conductive contact pads, allowing current to transfer. Two of the most common types of membrane keyboards include full-travel rubber dome over membrane and flat-panel membrane keyboards. Flat-panel membrane keyboards are most often found on appliances like microwave ovens or photocopiers . Full-travel rubber dome over membrane keyboards are

1692-614: The most common keyboard design manufactured today. In these keyboards, a rubber dome sheet is placed above the membranes, ensuring that the domes align with the contact pads. The rubber dome serves a dual purpose: it acts as a tactile return spring and provides a soft surface to transfer force onto the top membrane. To bridge the connection between the two contact pads, the rubber dome must be fully depressed. Rubber dome over membrane keyboards became very popular with computer manufacturers as they sought to reduce costs while PC prices declined. A common, compact variant of rubber dome over membrane

1739-441: The perimeter, mounted on a small PCB . The light is directed from side to side of the keyboard interior, and it can only be blocked by the actuated keys. Most optical keyboards require at least two beams (most commonly a vertical beam and a horizontal beam) to determine the actuated key. Some optical keyboards use a special key structure that blocks the light in a certain pattern, allowing only one beam per row of keys (most commonly

1786-417: The removal and replacement of keycaps with a common stem type. Almost all keyboards which utilize keys two or more units in length (such as the typical space bar or enter key) use stabilizers. Various lubricants and padding techniques can be used to reduce the rattle of components. A modern PC keyboard typically includes a control processor and indicator lights to provide feedback to the user about what state

1833-407: The risk of damage. When they are completely sealed in rubber, they are water resistant. Roll-up keyboards provide relatively little tactile feedback. Because these keyboards are typically made of silicone, they unfavorably tend to attract dirt, dust, and hair. Keyboards which have metal contact switches typically use discrete modules for each key. This type of switch are usually composed of a housing,

1880-403: The sensors send the information to the motherboard. Optical switch technology was introduced in 1962 by Harley E. Kelchner for use in a typewriter machine with the purpose of reducing the noise generated by typewriter keys. An optical keyboard technology utilizes light-emitting devices and photo sensors to optically detect actuated keys. Most commonly the emitters and sensors are located at

1927-492: The surface of the PCB, forming a daisy chain of two capacitors between contact pads and itself separated with a thin soldermask, and thus "shorting" the contact pads with an easily detectable drop of capacitive reactance between them. Usually, this permits a pulse or pulse train to be sensed. An advantage of the capacitive technology is that the switch is not dependent on the flow of current through metal contacts to actuate. There

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1974-426: The tape could only be used by 2 of 24 released programs. The MAX also lacks the serial and user ports necessary to connect a disk drive , printer , or modem . The lack of any built-in operating system , not even a simple bootstrap OS, combined with the fact that all the software released for the platform are video games (besides a scaled down cartridge-based BASIC with no disk, modem, or printer support) positions

2021-465: The text from an image to editable text (that is, a string of character codes), a person could re-type it, or a computer could look at the image and deduce what each character is. OCR technology has already reached an impressive state (for example, Google Book Search ) and promises more for the future. Speech recognition converts speech into machine-readable text (that is, a string of character codes). This technology has also reached an advanced state and

2068-402: Was intended to sell for around US$ 200. Although the MAX had better graphics and sound capability, Commodore's own VIC-20 , which sold for around the same amount, was much more expandable, had a much larger software library, and had a better keyboard—all of which made it more attractive to consumers. The MAX never sold well and was quickly discontinued. MAX Machine software list was limited, with

2115-501: Was originally invented in 1936 by W B Ellwood at Bell Telephone Laboratories . Although reed switches use metal leaf contacts, they are considered separate from all other forms of metal contact switch because the contacts are operated magnetically instead of using physical force from a slider to be pressed together. In a capacitive mechanism, pressing a key changes the capacitance of a pattern of capacitor pads. The pattern consists of two D-shaped capacitor pads for each switch, printed on

2162-420: Was the first to employ buckling spring key-switches, which used capacitive sensing to actuate. The original patent was never employed in an actual production keyboard but it establishes the basic premise of a buckling spring. The IBM Model M is a large family of computer keyboards created by IBM that began in late 1983 when IBM patented a membrane buckling spring key-switch design. The main intent of this design

2209-645: Was to halve the production cost of the Model F. The most well known full-size Model M is known officially as the IBM Enhanced Keyboard. In 1993, two years after spawning Lexmark , IBM transferred its keyboard operations to the daughter company. New Model M keyboards continued to be manufactured for IBM by Lexmark until 1996, when Unicomp was established and purchased the keyboard patents and tooling equipment to continue their production. IBM continued to make Model M's in their Scotland factory until 1999. When

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