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84-510: The IBM Personal Computer XT (model 5160, often shortened to PC/XT ) is the second computer in the IBM Personal Computer line, released on March 8, 1983. Except for the addition of a built-in hard drive and extra expansion slots, it is very similar to the original IBM PC model 5150 from 1981. IBM did not specify an expanded form of "XT" on the machine, press releases, brochures or documentation, but some publications expanded

168-417: A composite monitor. Text modes: IBM intended that CGA be compatible with a home television set. The 40 × 25 text and 320 × 200 graphics modes are usable with a television, and the 80 × 25 text and 640 × 200 graphics modes are intended for a monitor. CGA uses a 4-bit RGBI 16-color gamut , but not all colors are available at all times, depending on which graphics mode

252-468: A computer through retail channels rather than directly to customers. Because IBM did not have retail experience, they partnered with the retail chains ComputerLand and Sears , who provided important knowledge of the marketplace and became the main outlets for the PC. More than 190 ComputerLand stores already existed, while Sears was in the process of creating a handful of in-store computer centers for sale of

336-442: A dedicated power supply and included a hard drive. Although official hard drive support did not exist, the third party market did provide early hard drives that connected to the floppy disk controller , but required a patched version of PC DOS to support the larger disk sizes. The only option for human interface provided in the base PC was the built-in keyboard port, meant to connect to the included Model F keyboard. The Model F

420-692: A desktop case similar to that of the IBM PC. It weighs 32 pounds (15 kg) and is approximately 19.5 inches (50 cm) wide by 16 inches (41 cm) deep by 5.5 inches (14 cm) high. Similarly to the original IBM PC, the XT main board included a socket for the Intel 8087 floating point arithmetic coprocessor . This optional chip, when installed, greatly accelerated arithmetic for such applications as computer aided design or other software that required large amounts of arithmetical calculations. Only software that

504-524: A direct-drive monitor, the four color bits are output directly to the DE-9 connector at the back of the card. Within the monitor, the four signals are interpreted to drive the red, green and blue color guns. With respect to the RGBI color model described above, the monitor would translate the digital four-bit color number to some seven distinctive analog voltages in the range from 0.0 to 1.0 for each gun. Color 6

588-515: A four-color palette. In mode 4, there are two palettes, and in mode 5 there is a single palette. Several choices can be made by programming hardware registers. First, the selected palette. Second, the intensity – which is defined for the entire screen, not on a per-pixel basis. Third, color 0 (the "background" color) can be set to any of the 16 colors. The specific BIOS graphics mode influences which palettes are available. BIOS Mode 4 offers two palettes: green/red/brown and cyan/magenta/white. As with

672-535: A hard drive, the motherboard did not support BIOS expansion ROMs which was needed to support a hard drive controller, and both PC DOS and the BIOS had no support for hard disks. After the XT was released, IBM altered the design of the 5150 to add most of these capabilities, except for the upgraded power supply. At this point adding a hard drive was possible, but required the purchase of the IBM 5161 Expansion Unit, which contained

756-407: A higher scan rate. The effective screen resolution of this mode is 640 × 200 pixels. In this mode, the card has enough video RAM for four different text pages. As with the 40-column text modes, Mode 2 disables the color burst in the composite signal and Mode 3 enables it. Each character cell stored four bits for foreground and background color. However, in the card's default configuration,

840-567: A library of common functions that all software can use for many purposes, such as video output, keyboard input, disk access, interrupt handling, testing memory, and other functions. IBM shipped three versions of the BIOS throughout the PC's lifespan. While most home computers had built-in video output hardware, IBM took the unusual approach of offering two different graphics options, the MDA and CGA cards. The former provided high-resolution monochrome text, but could not display anything except text, while

924-401: A maximum of 64 KB onboard, and the more common 64 KB revision to a maximum of 256 KB on the motherboard. RAM cards could upgrade either variant further, for a total of 640 KB conventional memory , and possibly several megabytes of expanded memory beyond that, though on PC/XT-class machines, the latter was a very expensive third-party hardware option only available later in

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1008-657: A mouse.) Connectivity to other computers and peripherals was initially provided through serial and parallel ports. IBM provided a serial card based on an 8250 UART . The BIOS supports up to two serial ports. IBM provided two different options for connecting Centronics-compatible parallel printers. One was the IBM Printer Adapter, and the other was integrated into the MDA as the IBM Monochrome Display and Printer Adapter. The expansion capability of

1092-560: A normal means through the BASIC language to switch the CGA from blink mode to 16-background-color mode. This was still possible however by directly programming the hardware registers using the OUT statement of the BASIC language. CGA offers graphics modes at three resolutions: 160 × 100, 320 × 200 and 640 × 200. In all modes every pixel on the screen can be set directly, but

1176-693: A pattern of 8×8 dots. The effective screen resolution in this mode is 320 × 200 pixels (a pixel aspect ratio of 1:1.2.) The card has sufficient video RAM for eight different text pages in this mode. The difference between these two modes can only be seen on a composite monitor, where mode 0 disables the color burst, making all text appear in grayscale. Mode 1 enables the color burst, allowing for color. Mode 0 and Mode 1 are functionally identical on RGB monitors and on later adapters that emulate CGA without supporting composite color output. BIOS Modes 2 and 3 select 80 columns by 25 rows text modes, with each character still an 8×8 dot pattern, but displayed at

1260-467: A personal computer, possibly a miniaturized version of the IBM System/370 , and Matsushita acknowledged publicly that it had discussed with IBM the possibility of manufacturing a personal computer in partnership, although this project was abandoned. The public responded to these rumors with skepticism, owing to IBM's tendency towards slow-moving, bureaucratic business practices tailored towards

1344-505: A policy of strict secrecy, with all other IBM divisions kept in the dark about the project. Several CPUs were considered, including the Texas Instruments TMS9900 , Motorola 68000 and Intel 8088 . The 68000 was considered the best choice, but was not production-ready like the others. The IBM 801 RISC processor was also considered, since it was considerably more powerful than the other options, but rejected due to

1428-657: A rapidly changing market. The idea of acquiring Atari was considered but rejected in favor of a proposal by Lowe that by forming an independent internal working group and abandoning all traditional IBM methods, a design could be delivered within a year and a prototype within 30 days. The prototype worked poorly but was presented with a detailed business plan which proposed that the new computer have an open architecture , use non-proprietary components and software, and be sold through retail stores, all contrary to IBM practice. It also estimated sales of 220,000 computers over three years, more than IBM's entire installed base . This swayed

1512-595: A separate monochrome monitor for text menus. Third parties went on to provide an enormous variety of aftermarket graphics adapters, such as the Hercules Graphics Card . The software and hardware of the PC, at release, was designed around a single 8-bit adaptation of the ASCII character set, now known as code page 437 . The two bays in the front of the machine could be populated with one or two 5.25″ floppy disk drives, storing 160 KB per disk side for

1596-467: A substantial influence on the personal computer market ; the specifications of the IBM PC became one of the most popular computer design standards in the world. The only significant competition it faced from a non-compatible platform throughout the 1980s was from Apple 's Macintosh product line, as well as consumer-grade platforms created by companies like Commodore and Atari . Most present-day personal computers share architectural features in common with

1680-459: A total of 320 KB of storage on one disk. The floppy drives require a controller card inserted in an expansion slot, and connect with a single ribbon cable with two edge connectors. The IBM floppy controller card provides an external 37-pin D-sub connector for attachment of an external disk drive, although IBM did not offer one for purchase until 1986. As was common for home computers of the era,

1764-403: A year. By 1984, IBM's revenue from the PC market was $ 4 billion, more than twice that of Apple. A 1983 study of corporate customers found that two thirds of large customers standardizing on one computer chose the PC, while only 9% chose Apple. A 1985 Fortune survey found that 56% of American companies with personal computers used PCs while 16% used Apple. Almost as soon as the PC reached

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1848-498: Is an expansion chassis using an identical case and power supply to the XT, but instead of a system board, provides a backplane with eight card slots. It connects to the main system unit using an Extender Card in the system unit and a Receiver Card in the Expansion Unit, connected by a custom cable. The 5161 shipped with a 10 MB hard drive, and had room for a second one. The Expansion Unit can also contain extra memory, but

1932-509: Is being used. In the medium- and high-resolution modes, colors are stored at a lower bit depth and selected by fixed palette indexes, not direct selection from the full 16-color palette. When four bits are used (for low-resolution mode, or for programming color registers) they are arranged according to the RGBI color model: These four colour bits are then interpreted internally by the monitor, or converted to NTSC colours (see below). When using

2016-411: Is housed in a wide, short steel chassis intended to support the weight of a CRT monitor. The front panel is made of plastic, with an opening where one or two disk drives can be installed. The back panel houses a power inlet and switch, a keyboard connector, a cassette connector and a series of tall vertical slots with blank metal panels which can be removed in order to install expansion cards. Internally,

2100-417: Is not a graphics mode, but a tweak of the 80 × 25 text mode. The character cell height register is changed to display only two lines per character cell instead of the normal eight lines. This quadruples the number of text rows displayed from 25 to 100. These "tightly squeezed" text characters are not full characters. The system only displays their top two lines of pixels (eight each) before moving on to

2184-484: Is one bit, providing two colors which can be chosen from the 16-color palette by programming hardware registers. In this mode, the video picture is stored as a simple bitmap, with one bit per pixel setting the color to "foreground" or "background". By default the colors are black and bright white, but the foreground color can be changed to any entry in the 16-color CGA palette. The background color cannot be changed from black on an original IBM CGA card. This mode disables

2268-415: Is treated specially; normally, color 6 would become dark yellow , as seen to the left, but in order to achieve a more pleasing brown tone, special circuitry in most RGBI monitors, starting with the IBM 5153 color display, makes an exception for color 6 and changes its hue from dark yellow to brown by reducing the analogue green signal's amplitude. The exact amount of reduction differed between monitor models:

2352-534: The IBM 5153 color display, or to an NTSC -compatible television or composite video monitor via an RCA connector . The RCA connector provided only baseband video, so to connect the CGA card to a television set without a composite video input required a separate RF modulator . IBM produced the 5153 Personal Computer Color Display for use with the CGA, but this was not available at release and would not be released until March 1983. Although IBM's own color display

2436-583: The IBM PC compatible de facto standard . Released on August 12, 1981, it was created by a team of engineers and designers at International Business Machines (IBM), directed by William C. Lowe and Philip Don Estridge in Boca Raton, Florida . Powered by an x86 -architecture Intel 8088 processor, the machine was based on open architecture and third-party peripherals. Over time, expansion cards and software technology increased to support it. The PC had

2520-640: The IBM System/23 Datamaster . The 62-pin expansion bus slots were also designed to be similar to the Datamaster slots, and its keyboard design and layout became the Model F keyboard shipped with the PC, but otherwise the PC design differed in many ways. The 8088 motherboard was designed in 40 days, with a working prototype created in four months, demonstrated in January 1981. The design

2604-470: 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 ( TTL ) RGBI interface, such as

IBM Personal Computer XT - Misplaced Pages Continue

2688-587: The XT/370 ; they had an additional (co-)processor board that could execute System/370 instructions. An XT-based machine with a Series/1 co-processor board existed as well, but it had its own System Unit number, the IBM 4950 . In 1986, the XT 286 (model 5162) was released with a 6 MHz Intel 80286 processor. Despite being marketed as a lower-tier model than the IBM AT , this system runs many applications faster than

2772-506: The 5100 had a price tag as high as $ 20,000. Their entry into the home computer market needed to be competitively priced. In 1980, IBM president John Opel, recognizing the value of entering this growing market, assigned William C. Lowe and Philip Don Estridge as heads of the new Entry Level Systems unit in Boca Raton, Florida. Market research found that computer dealers were very interested in selling an IBM product, but they insisted

2856-464: The ATs of the time with 6 MHz 286 processors, since it has zero- wait state RAM. It shipped with 640 KB RAM standard, an AT-style 1.2 MB high-density diskette drive and a 20 MB hard disk. Despite these features, reviews rated it as a poor market value. The XT 286 uses a 157-watt power supply, which can internally switch between 115 or 230 V AC operation. Both the original XT and

2940-486: The CGA's onboard hardware into an NTSC-compatible signal fed to the card's RCA output jack. For cost reasons, this is not done using an RGB -to- YIQ converter as called for by the NTSC standard, but by a series of flip-flops and delay lines. Consequently, the hues seen are lacking in purity; notably, both cyan and yellow have a greenish tint, and color 6 again looks dark yellow instead of brown. The relative luminances of

3024-501: The CPU's I/O lines. IBM referred to these as "I/O slots", but after the expansion of the PC clone industry they became retroactively known as the ISA bus . At the back of the machine is a metal panel, integrated into the steel chassis of the system unit, with a series of vertical slots lined up with each card slot. Color Graphics Adapter The original IBM CGA graphics card was built around

3108-491: The Corporate Management Committee, which converted the group into a business unit named "Project Chess", and provided the necessary funding and authority to do whatever was needed to develop the computer in the given timeframe. The team received permission to expand to 150 people by the end of 1980, and in one day more than 500 IBM employees called in asking to join. The design process was kept under

3192-492: The Extender card inserts wait states for memory in the Expansion Unit, so it may be preferable to install memory into the main system unit. The 5161 can be connected to either an XT or to the earlier 5150 (the original IBM PC). PC DOS 2.0 offers a 9-sector floppy disk format, providing 180K/360K (single- vs. dual-sided) capacity per disk, compared to the 160K/320K provided by the 8-sector format of previous releases. The XT

3276-510: The IBM 5150's lifecycle and only usable with dedicated software support (i.e. only accessible via a RAM window in the Upper Memory Area ); this was relatively rarely equipped and utilized on the original IBM PC, much less fully so, thus the machine's maximum RAM configuration as commonly understood was 640 KB. The BIOS is the firmware of the IBM PC, occupying one 8 KB chip on the motherboard. It provides bootstrap code and

3360-575: The IBM Model M, but in a modified variant that used the XT's keyboard protocol and lacked LEDs). Submodels 267, 277 and 088 had the original keyboard, but 3.5" floppy drives became available and 20MB Seagate ST-225 hard disks in 5.25" half-height size replaced the full-height 10 MB drives. Submodel 788 was the only XT sold with the Color Graphics Adapter as a standard feature. Submodels 568, 588, and 589 were used as basis for

3444-435: The IBM PC offered a port for connecting a cassette data recorder . Unlike the typical home computer however, this was never a major avenue for software distribution, probably because very few PCs were sold without floppy drives. The port was removed on the very next PC model, the XT. At release, IBM did not offer any hard disk drive option and adding one was difficult - the PC's stock power supply had inadequate power to run

IBM Personal Computer XT - Misplaced Pages Continue

3528-399: The IBM PC was very significant to its success in the market. Some publications highlighted IBM's uncharacteristic decision to publish complete, thorough specifications of the system bus and memory map immediately on release, with the intention of fostering a market of compatible third-party hardware and software. The motherboard includes five 62-pin card edge connectors which are connected to

3612-462: The PC, covering such features as the bytecoding for color monitors, DMA access operation, and the keyboard interface. They were never enforced. Many of the designers were computer hobbyists who owned their own computers, including many Apple II owners, which influenced the decisions to design the computer with an open architecture and publish technical information so others could create compatible software and expansion slot peripherals. During

3696-557: The XT. The 3270 PC , a variant of the XT featuring 3270 terminal emulation, was released in October 1983. Submodel 068 and 078, released in 1985, offered dual-floppy configurations without a hard drive as well, and the new Enhanced Graphics Adapter and Professional Graphics Adapter became available as video card options. In 1986, the 256–640 KB motherboard models were launched, which switched to half-height drives. Submodels 268, 278 and 089 came with 101-key keyboards (essentially

3780-696: The XT/286 was discontinued in late 1987 after the launch of the IBM Personal System/2 (PS/2) line. The 8086-powered IBM PS/2 Model 30 served as the direct replacement for the XT in that PS/2 line. Unlike higher-end entries in the PS/2 line, which feature the Micro Channel expansion bus, the Model 30 contains 8-bit ISA bus slots, exactly like the XT. The XT was well received, although PC DOS 2.0

3864-517: The character and a "0" representing the background. These colors can be chosen independently, for each character on the screen, from the full 16-color CGA palette. The character set is defined by hardware code page 437 . The font bitmap data is only available to the card itself, it cannot be read by the CPU. In graphics modes, text output by the BIOS operates by copying text from the font ROM bit-by-bit to video memory. BIOS Modes 0 and 1 are both 40 columns by 25 rows text modes, with each character

3948-520: The chassis is dominated by a motherboard which houses the CPU, built-in RAM, expansion RAM sockets, and slots for expansion cards. The IBM PC was highly expandable and upgradeable, but the base factory configuration included: The PC is built around a single large circuit board called a motherboard which carries the processor, built-in RAM, expansion slots, keyboard and cassette ports, and the various peripheral integrated circuits that connected and controlled

4032-410: The color depth for the higher modes does not permit selecting freely from the full 16-color palette. The low-resolution 160 × 100 mode uses a 16-color palette and is set up as 80 × 25 character mode ( Mode 3 ) but uses memory-mapped graphics on 16 KB of memory. In the medium-resolution 320 × 200 modes ( Modes 4 and 5 ), each pixel is two bits, which select colors from

4116-401: The colors produced by the composite color-generating circuit differ between CGA revisions: they are identical for colors 1-6 and 9-14 with early CGAs produced until 1983, and are different for later CGAs due to the addition of additional resistors. CGA offers four BIOS text modes ( Modes 0 to 3 , called alphanumeric or A/N modes in IBM's documentation). In these modes, individual pixels on

4200-467: The company use a design based on standard parts, not IBM-designed ones so that stores could perform their own repairs rather than requiring customers to send machines back to IBM for service. Another source cites time pressure as the reason for the decision to use third-party components. Atari proposed to IBM in 1980 that it act as original equipment manufacturer for an IBM microcomputer, a potential solution to IBM's known inability to move quickly to meet

4284-567: The components of the machine. The peripheral chips included an Intel 8259 PIC , an Intel 8237 DMA controller, and an Intel 8253 PIT . The PIT provides 18.2 Hz clock "ticks" and dynamic memory refresh timing. The CPU is an Intel 8088 , a cost-reduced form of the Intel 8086 which largely retains the 8086's internal 16-bit logic, but exposes only an 8-bit bus. The CPU is clocked at 4.77 MHz, which would eventually become an issue when clones and later PC models offered higher CPU speeds that broke compatibility with software developed for

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4368-427: The composite color burst signal by default. The BIOS does not provide an option to turn the color burst on in 640 × 200 mode, and the user must write directly to the mode control register to enable it. A number of official and unofficial features exist that can be exploited to achieve special effects. Some of these above tweaks can be combined. Examples can be found in several games. Technically, this mode

4452-469: The design constraint to use off-the-shelf parts . The TMS9900 was rejected as it was inferior to the Intel 8088. IBM chose the 8088 over the similar but superior 8086 because Intel offered a better price for the former and could provide more units, and the 8088's 8-bit bus reduced the cost of the rest of the computer. The 8088 had the advantage that IBM already had familiarity with the 8085 from designing

4536-534: The design process IBM avoided vertical integration as much as possible, for example choosing to license Microsoft BASIC rather than utilizing the in-house version of BASIC used for mainframes due to the better existing public familiarity with the Microsoft version. The IBM PC debuted on August 12, 1981, after a twelve-month development. Pricing started at $ 1,565 for a configuration with 16 KB RAM, Color Graphics Adapter , keyboard, and no disk drives. The price

4620-402: The foreground and background colors. Using either character 221 or 222, each half of each truncated character cell can thus be treated as an individual pixel—making 160 horizontal pixels available per line. Thus, 160 × 100 pixels at 16 colors, with an aspect ratio of 1:1.2, are possible. Although a roundabout way of achieving a 16-color graphics display, this works quite well and

4704-470: The fourth bit of the background color does not set intensity, but sets the blink attribute for the cell. All characters on the screen with this bit set will periodically blink, meaning their foreground color will be changed to their background color so the character becomes invisible. All characters blink in unison. By setting a hardware register, the blink feature can be disabled, restoring access to high-intensity background colors. All blinking characters on

4788-450: The keyboard was extremely positive, with some sources describing it as a major selling point of the PC and even as "the best keyboard available on any microcomputer." At release, IBM provided a Game Control Adapter which offered a 15-pin port intended for the connection of up to two joysticks, each having two analog axes and two buttons. (The early PCs predated the advent of the " Windows, Icons, Mouse, Pointer" concept and so did not have

4872-411: The latter provided medium- and low-resolution color graphics and text. CGA used the same scan rate as NTSC television , allowing it to provide a composite video output which could be used with any compatible television or composite monitor , as well as a direct-drive TTL output suitable for use with any RGBI monitor using an NTSC scan rate. IBM also sold the 5153 color monitor for this purpose, but it

4956-554: The market, rumors of clones began, and the first legal PC-compatible clone—the MPC 1600 by Columbia Data Products —was released in June 1982, less than a year after the PC's debut. Eventually, IBM sold its PC business to Lenovo in 2004 . For low cost and a quick design turnaround time, the hardware design of the IBM PC used entirely "off-the-shelf" parts from third party manufacturers, rather than unique hardware designed by IBM. The PC

5040-515: The market, sold only 69,000. Software support from the industry grew rapidly, with the IBM nearly instantly becoming the primary target for most microcomputer software development. One publication counted 753 software packages available a year after the PC's release, four times as many as were available for the Macintosh a year after its launch. Hardware support also grew rapidly, with 30–40 companies competing to sell memory expansion cards within

5124-567: The most obvious use was the addition of an Intel 8087 math coprocessor, which improved floating-point math performance. PC mainboards were manufactured with the first memory bank of initially Mostek 4116-compatible, or later 4164-compatible DIP DRAMs soldered to the board, for a minimum configuration of first just 16 KB, or later 64 KB of RAM. Memory upgrades were provided by IBM and third parties both for socketed installation in three further onboard banks, and as ISA expansion cards. The early 16 KB mainboards could be upgraded to

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5208-415: The new product. Reception was overwhelmingly positive, with analysts estimating sales volume in the billions of dollars in the first few years after release. After release, IBM's PC immediately became the talk of the entire computing industry. Dealers were overwhelmed with orders, including customers offering pre-payment for machines with no guaranteed delivery date. By the time the machine began shipping,

5292-429: The next row. Character 221 of the CGA character set consists of a box occupying the entire left half of the character matrix. (Character 222 consists of a box occupying the entire right half.) Because each character can be assigned different foreground and background colors, it can be colored (for example) blue on the left (foreground color) and bright red on the right (background color). This can be reversed by swapping

5376-464: The original IBM 5153 Personal Computer Color Display reduces the green signal's amplitude by about one third, while the IBM 5154 Enhanced Color Display internally converts all 4-bit RGBI color numbers to 6-bit ECD color numbers, which amounts to halving the green signal's amplitude. The Tandy CM-2, CM-4 and CM-11 monitors provide a potentiometer labelled "BROWN ADJ." to adjust the amount of green signal reduction. This "RGBI with tweaked brown" palette

5460-430: The original IBM PC, including the Intel -based Mac computers manufactured from 2006 to 2022 . Prior to the 1980s, IBM had largely been known as a provider of business computer systems. As the 1980s opened, their market share in the growing minicomputer market failed to keep up with competitors, while other manufacturers were beginning to see impressive profits in the microcomputer space. The market for personal computers

5544-503: The original PC. The single base clock frequency for the system was 14.31818 MHz, which when divided by 3, yielded the 4.77 MHz for the CPU (which was considered close enough to the then 5 MHz limit of the 8088), and when divided by 4, yielded the required 3.579545 MHz for the NTSC color carrier frequency. The PC motherboard included a second, empty socket, described by IBM simply as an "auxiliary processor socket", although

5628-425: The problem by adding three extra expansion slots for a total of eight. While the slots themselves are identical to those in the original PC, the amount of physical space in the chassis differs, so two of the new slots (located behind the hard drive) cannot accept full-length cards. In addition, the spacing of the slots is narrower than in the original PC, making it impossible to install some multi-board cards. The 5161

5712-449: The production of large, sophisticated and expensive business systems. As with other large computer companies, its new products typically required about four to five years for development, and a well publicized quote from an industry analyst was, "IBM bringing out a personal computer would be like teaching an elephant to tap dance." IBM had previously produced microcomputers, such as 1975's IBM 5100 , but targeted them towards businesses;

5796-480: The screen blink in sync. The blinking attribute effect is enabled by default and the high-intensity background effect is disabled; disabling blinking is the only way to freely choose the latter eight-color indexes (8-15) for the background color. Notably, the GW-BASIC and Microsoft QBASIC programming languages included with MS-DOS supported all the text modes of the CGA with full color control, but did not provide

5880-405: The screen cannot be addressed directly. Instead, the screen is divided into a grid of character cells, each displaying a character defined in one of two bitmap fonts, "normal" and "thin," included in the card's ROM. The fonts are fixed and cannot be modified or selected from software, only by a jumper on the board itself. Fonts are stored as bitmaps at a color depth of 1-bit, with a "1" representing

5964-407: The term "PC" was becoming a household name. Sales exceeded IBM's expectations by as much as 800% (9x), with the company at one point shipping as many as 40,000 PCs per month. IBM estimated that home users made up 50 to 70% of purchases from retail stores. In 1983, IBM sold more than 750,000 machines, while Digital Equipment Corporation , one of the companies whose success had spurred IBM to enter

6048-408: The term as " eXtended Technology " or just " eXTended ". The XT was regarded as an incremental improvement over the PC and a disappointment compared to the next-generation successor that some had anticipated. Compared to the original IBM PC, the XT has the following major differences: Otherwise the specifications are identical to the original PC. The number of expansion slots in the original IBM PC

6132-408: The text modes 0 and 2, Mode 5 disables the color burst to allow colors to appear in grayscale on composite monitor. However, unlike the text modes, this also affects the colors displayed on an RGBI monitor, altering them to the cyan/red/white palette seen above. This palette is not documented by IBM, but was used in some software. In the high-resolution 640 × 200 mode ( Mode 6 ), each pixel

6216-510: Was a limiting factor for the product, since essential components (such as the video controller, disk controller and printer interface) each came as separate expansion cards and could quickly fill up all five available slots, requiring the user to swap cards in and out as tasks demanded. Some PC clones addressed this problem by integrating components into the motherboard to free up slots, while peripheral manufacturers produced products which integrated multiple functions into one card. The XT addressed

6300-402: Was designed to compete with comparable machines in the market. For comparison, the Datamaster, announced two weeks earlier as IBM's least expensive computer, cost $ 10,000. IBM's marketing campaign licensed the likeness of Charlie Chaplin 's character " The Little Tramp " for a series of advertisements based on Chaplin's movies, played by Billy Scudder. The PC was IBM's first attempt to sell

6384-538: Was dominated at the time by Tandy , Commodore , and Apple , whose machines sold for several hundred dollars each and had become very popular. The microcomputer market was large enough for IBM's attention, with $ 15 billion in sales by 1979 and projected annual growth of more than 40% during the early 1980s. Other large technology companies had entered it, such as Hewlett-Packard , Texas Instruments and Data General , and some large IBM customers were buying Apples. As early as 1980 there were rumors of IBM developing

6468-463: Was especially written to take advantage of the coprocessor would show a significant speedup. The power supply is 130 watts, an upgrade from the original PC. Those sold in the US were configured for 120 V AC only and could not be used with 240 V mains supplies. XTs with 240 V-compatible power supplies were later sold in international markets. Both were rated at 130 watts. IBM made several submodels of

6552-406: Was essentially complete by April 1981, when it was handed off to the manufacturing team. PCs were assembled in an IBM plant in Boca Raton, with components made at various IBM and third party factories. The monitor was an existing design from IBM Japan ; the printer was manufactured by Epson . Because none of the functional components were designed by IBM, they obtained only a handful of patents on

6636-540: Was initially developed for the IBM Datamaster , and was substantially better than the keyboards provided with virtually all home computers on the market at that time in many regards - number of keys, reliability and ergonomics. While some home computers of the time utilized chiclet keyboards or inexpensive mechanical designs, the IBM keyboard provided good ergonomics, reliable and positive tactile key mechanisms and flip-up feet to adjust its angle. Public reception of

6720-405: Was not available at release and was not released until March 1983. MDA scanned at a higher frequency and required a proprietary monitor, the IBM 5151 . The card also included a built-in printer port. Both cards could also be installed simultaneously for mixed graphics and text applications. For instance, AutoCAD , Lotus 1-2-3 and other software allowed use of a CGA Monitor for graphics and

6804-618: Was not available, customers could either use the composite output (with an RF modulator if needed), or the direct-drive output with available third-party monitors that supported the RGBI format and scan rate. Some third-party displays lacked the intensity input, reducing the number of available colors to eight, and many also lacked IBM's unique circuitry which rendered the dark-yellow color as brown, so any software which used brown would be displayed incorrectly. CGA offered several video modes. Graphics modes: Some software achieved greater color depth by utilizing artifact color when connected to

6888-523: Was not offered in a floppy-only model for its first two years on the market, although the standard ribbon cable with two floppy connectors was still included. At that time, in order to get a second floppy drive, the user had to purchase the 5161 expansion chassis. Like the original PC, the XT came with IBM BASIC in ROM . The XT BIOS also displays a memory count during the POST , unlike the original PC. The XT has

6972-462: Was regarded as a greater improvement than any of the hardware changes, and by the end of 1983 IBM was selling every unit they made. By 1985 the IBM PC AT made the XT obsolete for most customers. Photo galleries: IBM Personal Computer The IBM Personal Computer (model 5150, commonly known as the IBM PC ) is the first microcomputer released in the IBM PC model line and the basis for

7056-405: Was retained as the default palette of later PC graphics standards such as EGA and VGA , which can select colors from much larger gamuts, but default to these until reprogrammed. Later video cards/monitors in CGA emulation modes would approximate the colors with the following formula: which yields the canonical CGA palette: For the composite output, these four-bit color numbers are encoded by

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