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Monochrome Display Adapter
The Monochrome Display Adapter (MDA, also MDA card, Monochrome Display and Printer Adapter, MDPA) is IBM's standard video display card and computer display standard for the IBM PC introduced in 1981. The MDA does not have any pixel-addressable graphics modes, only a single monochrome text mode which can display 80 columns by 25 lines of high-resolution text characters or Semigraphics, symbols useful for drawing forms. Hardware design The original IBM MDA was an 8-bit ISA card with a Motorola 6845 display controller, 4 KB of RAM, a D-subminiature, DE-9 output port intended for use with an IBM 5151, IBM monochrome monitor. A parallel port for attachment of a printer is also included, avoiding the need to purchase a separate card. Capabilities The MDA was based on the IBM System/23 Datamaster's display system, and was intended to support business and word processing use with its sharp, high-resolution characters. Each character is rendered in a box of 9 × ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorola 6845
The Motorola 6845, or MC6845, is a display controller that was widely used in 8-bit computers during the 1980s. Originally intended for designs based on the Motorola 6800 CPU and given a related part number, it was more widely used alongside various other processors, and was most commonly found in machines based on the Zilog Z80 and MOS 6502. The 6845 is not an entire display solution on its own; the chip's main function is to properly time access to the display memory, and to calculate the memory address of the next portion to be drawn. Other circuitry in the machine then uses the address provided by the 6845 to fetch the pattern and then draw it. The implementation of that hardware is entirely up to the designer and varied widely among machines. The 6845 is intended for character displays, but could also be used for pixel-based graphics, with some clever programming. Among its better-known uses are the BBC Micro, Amstrad CPC, and Videx VideoTerm display cards for the Apple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Word Processing
A word processor (WP) is a device or computer program that provides for input, editing, formatting, and output of text, often with some additional features. Word processor (electronic device), Early word processors were stand-alone devices dedicated to the function, but current word processors are word processor programs running on general purpose computers, including smartphones, tablets, laptops and desktop computers. The functions of a word processor program are typically between those of a simple text editor and a desktop publishing program; Many word processing programs have gained advanced features over time providing similar functionality to desktop publishing programs. Common word processor programs include LibreOffice Writer, Google Docs and Microsoft Word. Background Word processors developed from mechanical machines, later merging with computer technology. The history of word processing is the story of the gradual automation of the physical aspects of writing and edit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Graphics Adapter
The Color Graphics Adapter (CGA), originally also called the ''Color/Graphics Adapter'' or ''IBM Color/Graphics Monitor Adapter'', introduced in 1981, was IBM's first color graphics card for the IBM PC and established a De facto standard, de facto computer display standard. Hardware design The original IBM CGA graphics card was built around the Motorola 6845 display controller, came with 16 kilobytes of video memory built in, and featured several graphics and text modes. The highest display resolution of any mode was 640 × 200, and the highest color depth supported was 4-bit (16 colors). The CGA card could be connected either to a direct-drive CRT monitor using a 4-bit digital (Transistor-transistor logic, TTL) RGB(I), RGBI interface, such as the IBM 5153 color display, or to an NTSC-compatible television or composite video computer monitor, monitor via an RCA connector. The RCA connector provided only baseband video, so to connect the CGA card to a television set w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM PC 5150
International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is a publicly traded company and one of the 30 companies in the Dow Jones Industrial Average. IBM is the largest industrial research organization in the world, with 19 research facilities across a dozen countries; for 29 consecutive years, from 1993 to 2021, it held the record for most annual U.S. patents generated by a business. IBM was founded in 1911 as the Computing-Tabulating-Recording Company (CTR), a holding company of manufacturers of record-keeping and measuring systems. It was renamed "International Business Machines" in 1924 and soon became the leading manufacturer of punch-card tabulating systems. During the 1960s and 1970s, the IBM mainframe, exemplified by the System/360 and its successors, was the world's dominant computing platform, with the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luma (video)
In video, luma (Y') represents the brightness in an image (the "black-and-white" or achromatic portion of the image). Luma is typically paired with chrominance. Luma represents the grey, achromatic image, while the chroma components represent the color information. Converting RGB color model, R′G′B′ sources (such as the output of a three-CCD camera) into luma and chroma allows for chroma subsampling: because human vision has finer spatial sensitivity to luminance ("black and white") differences than chromatic differences, video systems can store and transmit chromatic information at lower resolution, optimizing perceived detail at a particular bandwidth. Luma versus relative luminance Luma is the weighted sum of gamma-compressed R′G′B′ components of a color video—the ''prime symbols'' ′ denote Gamma correction, gamma compression. The word was proposed to prevent confusion between luma as implemented in video engineering and relative luminance as used in color s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transistor–transistor Logic
Transistor–transistor logic (TTL) is a logic family built from bipolar junction transistors (BJTs). Its name signifies that transistors perform both the logic function (the first "transistor") and the amplifying function (the second "transistor"), as opposed to earlier resistor–transistor logic (RTL) and diode–transistor logic (DTL). TTL integrated circuits (ICs) were widely used in applications such as computers, industrial controls, test equipment and instrumentation, consumer electronics, and synthesizers. After their introduction in integrated circuit form in 1963 by Sylvania Electric Products, TTL integrated circuits were manufactured by several semiconductor companies. The 7400 series by Texas Instruments became particularly popular. TTL manufacturers offered a wide range of logic gates, flip-flops, counters, and other circuits. Variations of the original TTL circuit design offered higher speed or lower power dissipation to allow design optimization. TTL devices w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse Video
Reverse video (or invert video or inverse video or reverse screen) is a computer display technique whereby the background and text color values are inverted. On older computers, displays were usually designed to display text on a black background by default. For emphasis, the color scheme was swapped to bright background with dark text. Nowadays the two tend to be switched, since most computers today default to white as a background color. The opposite of reverse video is known as ''true video''. Video is usually reversed by inverting the brightness values of the pixels of the involved region of the display. If there are 256 levels of brightness, encoded as 0 to 255, the 255 value becomes 0 and vice versa. A value of 1 becomes 254, 2 of 253, and so on: ''n'' is swapped for ''r'' - ''n'', for ''r'' levels of brightness. This is occasionally called a ones' complement. If the source image is of middle brightness, reverse video can be difficult to see, 127 becomes 128 for example, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Box-drawing Characters
Box-drawing characters, also known as line-drawing characters, are a form of semigraphics widely used in text user interfaces to draw various geometric frames and boxes. These characters are characterized by being designed to be connected horizontally and/or vertically with adjacent characters, which requires proper alignment. Box-drawing characters therefore typically only work well with monospaced fonts. In graphical user interfaces, these characters are much less useful as it is simpler to draw lines and rectangles directly with graphical APIs. However, they are still useful for command-line interfaces and plaintext Comment (computer programming), comments within source code. Some recent embedded systems also use proprietary character sets, usually extensions to ISO 8859 character sets, which include box-drawing characters or other special symbols. Other types of box-drawing characters are block elements, shade characters, and terminal graphic characters; these can be used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASCII
ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control characters a total of 128 code points. The set of available punctuation had significant impact on the syntax of computer languages and text markup. ASCII hugely influenced the design of character sets used by modern computers; for example, the first 128 code points of Unicode are the same as ASCII. ASCII encodes each code-point as a value from 0 to 127 storable as a seven-bit integer. Ninety-five code-points are printable, including digits ''0'' to ''9'', lowercase letters ''a'' to ''z'', uppercase letters ''A'' to ''Z'', and commonly used punctuation symbols. For example, the letter is represented as 105 (decimal). Also, ASCII specifies 33 non-printing control codes which originated with ; most of which are now obsolete. The control cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Code Page 437
Code page 437 ( CCSID 437) is the character set of the original IBM PC (personal computer). It is also known as CP437, OEM-US, OEM 437, PC-8, or MS-DOS Latin US. The set includes all printable ASCII characters as well as some accented letters (diacritics), Greek letters, icons, and line-drawing symbols. It is sometimes referred to as the "OEM font" or "high ASCII", or as "extended ASCII" (one of many mutually incompatible ASCII extensions). This character set remains the primary set in the core of any EGA and VGA-compatible graphics card. As such, text shown when a PC reboots, before fonts can be loaded and rendered, is typically rendered using this character set. Many file formats developed at the time of the IBM PC are based on code page 437 as well. Display adapters The original IBM PC contained this font as a 9×14 pixels-per-character font stored in the ROM of the IBM Monochrome Display Adapter (MDA) and an 8×8 pixels-per-character font of the Color Graphics Adapter ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASCII Art
ASCII art is a graphic design technique that uses computers for presentation and consists of pictures pieced together from the 95 printable (from a total of 128) character (computing), characters defined by the ASCII Standard from 1963 and ASCII compliant character sets with proprietary extended characters (beyond the 128 characters of standard 7-bit ASCII). The term is also loosely used to refer to #Other text-based visual art, text-based visual art in general. ASCII art can be created with any text editor, and is often used with free-form languages. Most examples of ASCII art require a Monospaced font, fixed-width font (non-proportional typeface, fonts, as on a traditional typewriter) such as Courier (typeface), Courier or Consolas for presentation. Among the oldest known examples of ASCII art are the creations by computer-art pioneer Kenneth Knowlton from around 1966, who was working for Bell Labs at the time. "Studies in Perception I" by Knowlton and Leon Harmon from 1966 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Code Page 437
Code page 437 ( CCSID 437) is the character set of the original IBM PC (personal computer). It is also known as CP437, OEM-US, OEM 437, PC-8, or MS-DOS Latin US. The set includes all printable ASCII characters as well as some accented letters (diacritics), Greek letters, icons, and line-drawing symbols. It is sometimes referred to as the "OEM font" or "high ASCII", or as "extended ASCII" (one of many mutually incompatible ASCII extensions). This character set remains the primary set in the core of any EGA and VGA-compatible graphics card. As such, text shown when a PC reboots, before fonts can be loaded and rendered, is typically rendered using this character set. Many file formats developed at the time of the IBM PC are based on code page 437 as well. Display adapters The original IBM PC contained this font as a 9×14 pixels-per-character font stored in the ROM of the IBM Monochrome Display Adapter (MDA) and an 8×8 pixels-per-character font of the Color Graphics Adapter ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
