History Platform / IBMPersonalComputer

The other big influence on the IBM PC's design was the world of ''S-100 machines'', which were based around the Intel 8080 (or, later the Zilog Z80) and the "S-100" bus that had been introduced in the pioneering Altair 8800. These machines ran an OS called ''CP/M'', which had been invented by a programmer named Gary Kildall in 1974 and was based indirectly on Digital Equipment Corp.'s various [[UsefulNotes/OperatingSystem operating systems]] for their [[UsefulNotes/MainframesAndMinicomputers PDP series of minicomputers]]. While they weren't nearly as slick as the Platform/AppleII, S-100 machines were popular with hobbyists and businesses alike, and several CP/M applications for businesses, like ''[=WordStar=]'' and ''[=dBASE=]'', were making inroads.

* 64K [[UsefulNotes/RandomAccessMemory RAM]], expandable to 640K; some expansion systems could backfill up to 736K if you were using an MDA. Later programs allowed use of backfilling on CGA displays using the UMA memory scheme, assuming additional RAM chips to push the machine past 640k are installed. [[http://philipstorr.id.au/pcbook/showtell/show2.htm Memory can be further increased]] with EMS memory cards that plugged into the expansion slots, each card can hold up to 2MB of EMS memory and used bank-switching to swap data in and out of a specially allocated 64k memory region above the 640k conventional RAM area but below the 1MB limit.

* It ran MS-DOS: a single-task, 16-bit UsefulNotes/OperatingSystem that in its early days was basically a clone of Digital Research's CP/M, and didn't actually provide much in the way of an API except for a file system and limited memory management. Everything else was up to the programmer.

* ''VideoGame/{{Biomenace}}''

In the mid-1990s there was another competitor bus, VESA[[note]]see the note above under Super VGA[[/note]] Local Bus (or VLB for short), which added a 32-bit wide, full-speed side channel to the ISA bus. VLB was originally designed to give bandwidth-hungry UsefulNotes/{{GPU}}s a faster connection to the system bus, but it was also something of a stopgap measure and didn't last long. Its biggest problem was that it was too deeply connected to the internals of the 486 processor, for which it was developed; the Pentium used a completely different memory bus setup, and converting between the two was notoriously difficult. Also, VLB's specification was not very rigid and almost all manufacturers tweaked it a bit. This lack of precision also made running anything other than video on VLB a potentially dangerous proposition, especially if UsefulNotes/MassStorage was involved; most IDE controllers of the day generated their timing signals directly from the VLB, and if it was running faster than what the controller expected, bad things (such as missed interrupts) would happen. VLB also had mechanical problems. Physically, it was a high-density edge connector positioned next to (and on the far side of) an ISA-16 slot, so it could be used with full-length cards only (giving it a FanNickname of [[FunWithAcronyms "Very Long Bus"]]); since many cases of the day weren't designed with full-length cards in mind, inserting a VLB card was often quite difficult and risked damaging the card, the motherboard, or the case.

The introduction of Windows 3.0 in 1990 also finally made Windows a legitimate platform after several years of false starts; it placed higher demands on both [[UsefulNotes/{{GPU}} graphics hardware]] and UsefulNotes/MassStorage, and it was this need for better hardware that drove PC development.

With the introduction of VESA Local Bus and then PCI between 1993 and 1995, along with improved video, sound and storage hardware, the PC started to look less like a classic 8-bit computer with bolted-on upgrades and more like a high-end RISC workstation. The introduction of the second-wave Pentium in 1995 and the Pentium II and AMD K6 in 1997, along with the ACPI UsefulNotes/ApplicationProgrammingInterface in 1998, blurred the distinctions even further, and convinced people that a cheap desktop could perform as well as an expensive UNIX workstation. AMD sweetened the deal further in 1999 with the announcement of the "x86-64" instruction set, which added 64-bit capability to the PC and fixed some of the 80x86's long-standing quirks; the first CPU to feature it was the Opteron, released in 2003.

Then in 1995, the 3D craze hit. While pseudo-3D graphics had been around for a while at this point in the form of ''Wolfenstein 3D'', ''Doom'' and its various clones, the rise of multimedia, as well as hype caused by the first generation of VR glasses hitting the market and the seminal 1995 computer-animated film ''WesternAnimation/ToyStory1'', caused gamers to crave better, more realistic 3D. A startup called Nvidia released a 3D chip called the [=NV1=]. It was quickly picked up by Diamond Technologies who were looking to make their card stand out of the then already saturated "graphics accelerator" market. The card proved to be rather impressive, as it could replace both the video card and the sound card, and produced beautiful and fluid 3D graphics, but ultimately it was a flop due to the oddball choice of quadrilateral polygons, which sent both Nvidia and Diamond back to the drawing board when [[UsefulNotes/ApplicationProgrammingInterface DirectX]] chose the more traditional triangular polygons when it was ratified instead.

* Optional MDA, CGA, EGA or the rare and expensive Professional Graphics Controller, an early UsefulNotes/{{GPU}} meant for CAD use. EGA was a major upgrade over the CGA, which finally brought high resolution (640×350) color graphics to the platform. EGA could display 16 colors out of a 64-color palette, and despite being pretty awkward to program,[[note]]It used 4-bit color, with one bit for each channel and a fourth bit for brightness, but for hardware reasons it kept each channel in its own memory segment, called bit/color planes. It made for cheaper design of the controller itself, but made it pretty hard to program.[[/note]] the stock mode carried a then-huge 64K of UsefulNotes/VideoRAM and allowed a clever programmer[[note]]Like Creator/JohnCarmack in ''VideoGame/CommanderKeen''[[/note]] to do tricks in software that were previously thought possible only on the consoles with their hardware accelerators, like smooth scrolling. However, due to the way the monitor interface was implemented, 64-color support was only guaranteed to work in 640×350 mode, which required at least 128K VRAM and worked best with the full complement of 256K.[[note]]6-bit color has been shown to work in 200-line mode on some combinations of the original IBM EGA and Enhanced Color Display, but this should be considered a hack, since the spec only expects the 16 CGA colors to work.[[/note]] While many third-party cards shipped with 256K, most of IBM's didn't; between that and the need for an Enhanced Color Display, 640×350 mode was mainly used for office programs and professional work.

Games that are run through DOS. These remained popular until the mid-90's when Windows replaced DOS as the OS on most computers. Windows has tried to keep compatibility with them throughout the years; however, with Windows no longer being DOS based, along with the move to 64-bit versions of Windows that don't support older 16-bit programs, the use of an UsefulNotes/{{emulat|ion}}or (such as UsefulNotes/DOSBox) is required at this point.

* ''VideoGame/{{Commando}}''

In a burst of brilliance, the engineers of the PC decided to make it possible to install ''both'' MDA and CGA cards in the same machine, creating [[OlderThanTheyThink the earliest instance ever of a multi-monitor PC setup]]. While the setup was pricey, [[note]]as it needed two monitors as well as both the MDA and CGA cards[[/note]] tricky to configure, [[note]]the ANSI.SYS driver must be loaded into memory, then the MODE command be invoked to select the desired display[[/note]] and required more desk space than a typical setup of the time, many professional-grade software packages (mostly desktop publishing, engineering and development software) could take advantage of the setup. Unfortunately, many consumer-grade software programs, especially games, were designed to presume only the CGA card was installed and did arcane things in the memory space normally used by the MDA card. This caused issues that ranged from glitching to outright system crashes when said software was run on a PC with both cards installed, relegating such configurations to the offices of professionals until Windows 98 revived the idea by offering official support for multiple [=GPUs=] and spreading the desktop across multiple monitors.

IBM followed up the PC with the XT in 1983, which removed the original PC's cassette interface, added more expansion slots (along with an optional expansion chassis), and made a hard drive option available. 1983 also saw the introduction of the ''[[Platform/IBMPCjr PCjr]]'', a severely crippled version of the XT intended for home use; its main claims to fame were the addition of a 16-color, 320×200 graphics mode and an internal [[UsefulNotes/GamingAudio 4-voice PSG]] (the same Texas Instruments model used in their own Platform/TI99 series and, more famously, in the Platform/ColecoVision), both of which inspired one of the most famous clone families, the Platform/Tandy1000. Next was the PC/AT in 1984, which introduced the 80286 processor and a fully 16-bit architecture, along with the Enhanced Graphics Adapter (EGA), which finally made 16-color graphics (in resolutions all the way up to 640×350, although 320x200 and 320x240 were the most popular resolutions) possible on a regular PC. And with ''that'', with the capacity for attractive applications and especially entertainment software, the march of history began...

"IBM compatible" became to the personal computer industry what VHS was to the UsefulNotes/{{VCR}} in the '80s. While some other platforms might have been technically better, that didn't matter compared to the huge variety of software and hardware peripherals available for the PC, much like how the main advantage of VHS was the large amount of content available for it. The PC (or more importantly MS-DOS on x86 processors) became a de-facto standard everyone rallied around, and proved to be a safe bet for new companies entering the computer market. The earliest clone manufacturers were Eagle, Columbia Data Products and Compaq. A number of small mom-and-pop operations sprang up using cheap parts from Asia.