The Indus GT is a 5 + 1 ⁄ 4 -inch floppy disk drive that was introduced by Indus Systems in 1983 for the Atari 8-bit computers . It was later released for the Apple II and Commodore 64 . On the Atari, it was widely regarded as the best drive of the era, with the most features, highest performance, and even best industrial design. They were known for the advertising slogan, "Turn your Atari into a Ferrari." The GT was sold until around 1987, at which point the rights were sold to Logical Design Works and reintroduced as the LDW Super 2000, sold primarily into Poland , and the CA-2001, sold into the US.
27-426: The GT drive is housed in a black metal case and the opening in the front for the floppy was covered by a flip-open smoked plexiglass door that makes the unit look completely sealed when closed. A two-digit seven-segment LED display is on the face of the unit behind the door, but remains readable even with the door closed. Buttons beside the display allow the user to select among track number, most recent error code, and
54-412: A diameter of up to 300 mm. These wafers are then polished to a mirror finish before going through photolithography . In many steps the transistors are manufactured and connected with metal interconnect layers. These prepared wafers then go through wafer testing to test their functionality. The wafers are then sliced and sorted to filter out the faulty dies. Functional dies are then packaged and
81-597: A limited number of segments in seven-segment displays, a couple of the hexadecimal digits are required to be displayed as lowercase letters, otherwise the uppercase letter "B" would be the same as the digit "8", and the uppercase letter "D" would be the same as the digit "0". The digit "6" must also be displayed with the topmost segment as [REDACTED] to avoid ambiguity with the letter "b". Early decoder IC's often produced random patterns or duplicates of digits for 10-15, as they were designed to use as few gates as possible and only required to produce 0-9. Many letters of
108-441: A method of telegraphically transmitting letters and numbers and having them printed on tape in a segmented format. In 1908, F. W. Wood invented an 8-segment display, which displayed the number 4 using a diagonal bar ( U.S. patent 974,943 ). In 1910, a seven-segment display illuminated by incandescent bulbs was used on a power-plant boiler room signal panel. They were also used to show the dialed telephone number to operators during
135-447: A rectangle, with two vertical segments on each side and one horizontal segment each at the top, middle, and bottom. Often the rectangle is oblique (slanted), which may aid readability. In most applications, the segments are of nearly uniform shape and size (usually elongated hexagons , though trapezoids and rectangles can also be used); though in the case of adding machines , the vertical segments are longer and more oddly shaped at
162-734: A restricted range of letters that look like (upside-down) digits, seven-segment displays are commonly used by school children to form words and phrases using a technique known as " calculator spelling ". Seven-segment displays may use a liquid-crystal display (LCD), a light-emitting diode (LED) for each segment, an electrochromic display , or other light-generating or -controlling techniques such as cold cathode gas discharge (neon) ( Panaplex ), vacuum fluorescent (VFD), incandescent filaments (Numitron), and others. For gasoline price totems and other large signs, electromechanical seven-segment displays made up of electromagnetically flipped light-reflecting segments are still commonly used. A precursor to
189-461: A seven-segment digit template , to compose figures such as product prices or telephone numbers. For many applications, dot-matrix liquid-crystal displays (LCDs) have largely superseded LED displays in general, though even in LCDs, seven-segment displays are common. Unlike LEDs, the shapes of elements in an LCD panel are arbitrary since they are formed on the display by photolithography . In contrast,
216-446: A seven-segment display, including the decimal point. The most popular bit encodings are gfedcba and abcdefg . In the gfedcba representation, a byte value of 0x06 would turn on segments "c" and "b", which would display a "1". The numerical digits 0 to 9 are the most common characters displayed on seven-segment displays. The most common patterns used for each of these are: Alternative patterns: The numeral 1 may be represented with
243-640: A simple LED package, typically all of the cathodes (negative terminals) or all of the anodes (positive terminals) of the segment LEDs are connected and brought out to a common pin; this is referred to as a "common cathode" or "common anode" device. Hence a 7 segment plus decimal point package will only require nine pins, though commercial products typically contain more pins, and/or spaces where pins would go, in order to match standard IC sockets. Integrated displays also exist, with single or multiple digits. Some of these integrated displays incorporate their own internal decoder , though most do not: each individual LED
270-454: Is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays . Seven-segment displays are widely used in digital clocks , electronic meters, basic calculators, and other electronic devices that display numerical information. Seven-segment representation of figures can be found in patents as early as 1903 (in U.S. patent 1,126,641 ), when Carl Kinsley invented
297-468: Is brought out to a connecting pin as described. Multiple-digit LED displays as used in pocket calculators and similar devices used multiplexed displays to reduce the number of I/O pins required to control the display. For example, all the anodes of the A segments of each digit position would be connected together and to a driver circuit pin, while the cathodes of all segments for each digit would be connected. To operate any particular segment of any digit,
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#1732801117862324-491: Is cut ( diced ) into many pieces, each containing one copy of the circuit. Each of these pieces is called a die. There are three commonly used plural forms: dice , dies, and die . To simplify handling and integration onto a printed circuit board , most dies are packaged in various forms . Most dies are composed of silicon and used for integrated circuits. The process begins with the production of monocrystalline silicon ingots. These ingots are then sliced into disks with
351-437: The latin alphabet can be reasonably implemented on a seven-segment display. Though not every letter is available, it is possible to create many useful words. By careful choice of words, one can sometimes work around unavailable letters. Uppercase letters "I", "O", "S", "Z" conflict with the common seven-segment representation of digits "1", "0", 5", "2", and the lowercase letter "g" with digit "9". Upper case I could be put on
378-517: The "enhanced" density mode introduced on the Atari 1050 , although the drive itself could be used with such disks if the host machine was booted with Atari DOS 2.5 instead of DOS XL. Indus later introduced their own speed improvement, "Synchromesh", which doubled the transfer speed over the SIO bus to 38.4 kbit/s. A later version, "SuperSynchromesh", improved this further to 68 kbit/s. One complaint
405-442: The 1970s. Many early (c. 1970s) LED seven-segment displays had each digit built on a single die . This made the digits very small. Some included magnifying lenses in the design to try to make the digits more legible. Other designs used 1 or 2 dies for every segment of the display. The seven-segment pattern is sometimes used in posters or tags, where the user either applies color to pre-printed segments, or applies color through
432-464: The 7-segment display in the 1950s through the 1970s was the cold-cathode, neon-lamp-like nixie tube . Starting in 1970, RCA sold a display device known as the Numitron that used incandescent filaments arranged into a seven-segment display. In USSR, the first electronic calculator "Vega", which was produced from 1964, contains 20 decimal digits with seven-segment electroluminescent display . In
459-487: The RAMCharger, added 64 kB of random-access memory (RAM) and a PAL chip that allowed the drive to run CP/M software. For Atari users, the drive shipped with DOS XL from Optimized Systems Software , authors of the original Atari DOS . DOS XL added support for double-density disks although it could still format and read and write single-density disks for use with other Atari drives. It did not, however, support
486-464: The controlling integrated circuit would turn on the cathode driver for the selected digit, and the anode drivers for the desired segments; then after a short blanking interval the next digit would be selected and new segments lit, in a sequential fashion. In this manner an eight digit display with seven segments and a decimal point would require only 8 cathode drivers and 8 anode drivers, instead of sixty-four drivers and IC pins. Often in pocket calculators
513-502: The digit drive lines would be used to scan the keyboard as well, providing further savings; however, pressing multiple keys at once would produce odd results on the multiplexed display. Although to a naked eye all digits of an LED display appear lit, only one digit is lit at any given time in a multiplexed display. The digit changes at a high enough rate that the human eye cannot see the flashing (on earlier devices it could be visible to peripheral vision). The seven segments are arranged as
540-463: The ends, to try to make them more easily readable. The seven elements of the display can be lit in different combinations to represent each of the Arabic numerals . The individual segments are referred to by the letters "a" to "g", and an optional decimal point (an "eighth segment", referred to as DP) is sometimes used for the display of non-integer numbers. A single byte can encode the full state of
567-498: The full ASCII character set were briefly available in the early 1980s but did not prove popular. Die (integrated circuit) A die , in the context of integrated circuits , is a small block of semiconducting material on which a given functional circuit is fabricated . Typically, integrated circuits are produced in large batches on a single wafer of electronic-grade silicon (EGS) or other semiconductor (such as GaAs ) through processes such as photolithography . The wafer
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#1732801117862594-439: The left (as lower-case L is shown here) but this is not often done. Lowercase 'b' and 'q' are identical to the alternate numerical digits '6' and '9'. The following are some real world english word examples seen on actual electronic equipment: There are also fourteen- and sixteen-segment displays (for full alphanumerics ); however, these have mostly been replaced by dot matrix displays . 22-segment displays capable of displaying
621-682: The left segments, the numerals 6 and 9 may be represented without a "tail", and the numeral 7 represented with a 'tail': In Unicode 13.0, 10 codepoints had been given for segmented digits 0–9 in the Symbols for Legacy Computing block, to replicate early computer fonts that included seven-segment versions of the digits. The official reference shows the less-common four-segment "7". The binary-coded decimal (BCD) 0 to 9 digit values require four binary bits to hold their values. Since four bits (2 ) can hold 16 values, this means hexadecimal (hex) digits can be represented by four bits too. Since there are
648-639: The shapes of LED segments tend to be simple rectangles , because they have to be physically moulded to shape, which makes it difficult to form more complex shapes than the segments of seven-segment displays. However, the easy recognition of seven-segment displays, and the comparatively high visual contrast obtained by such displays relative to dot-matrix digits, makes seven-segment multiple-digit LCD screens very common on basic calculators . The seven-segment display has inspired type designers to produce typefaces reminiscent of that display (but more legible), such as New Alphabet , "DB LCD Temp", "ION B", etc. Using
675-769: The transition from manual to automatic telephone dialing. They did not achieve widespread use until the advent of LEDs in the 1970s. Some early seven-segment displays used incandescent filaments in an evacuated bulb; they are also known as numitrons. A variation (minitrons) made use of an evacuated potted box. Minitrons are filament segment displays that are housed in DIP ( dual in-line package ) packages like modern LED segment displays. They may have up to 16 segments . There were also segment displays that used small incandescent light bulbs instead of LEDs or incandescent filaments. These worked similarly to modern LED segment displays. Vacuum fluorescent display versions were also used in
702-470: The type of formatting on the disk, single, enhanced (or dual), or double-density. A fourth button enables write protection, while a real-panel switch lets the user to select the default format. The drive was based on the Tandon TM50 half-height mechanism connected to a Western Digital 2797 drive controller. The connection to the host computer was controlled by a Zilog Z80 . A later upgrade from Indus,
729-637: Was that the Synchromesh software took a long time to load, so modified boot disks appeared to improve this. It was considered a high-quality unit, regarded by many as the best floppy drive available for 8-bit Ataris. It was advertised as being over 400% as fast as the Commodore 1541 and has an internal "ROM drive" with DOS utility software, but suffers, as do many third-party Commodore-1541-imitation drives, from being less than 100% 1541-compatible. Seven-segment display A seven-segment display
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