The PlayStation 2 (PS2) (Japanese: プレイステーション2) is Sony's second video game console, after the PlayStation. Its development was announced in April 1999, and it was first released in Japan on March 4th 2000. The console model for Japan was Silver instead of Black. The US version was released in the United States on October 26th 2000. For the first year Sony had slow production and was plagued with shipping problems when it was released. Only a selected few obtained the PlayStation 2 by the end of 2000. Developers also complained about the system being too hard to develop for. Later Sony gained steam with new development kits for game developers and more PlayStations for consumers. The PlayStation 2 is currently by far the most popular gaming console of the sixth generation era, with over 80 million units sold.
The PlayStation brand's strength has lead to strong third-party support for the system. Among the perceived killer apps on the machine are the Grand Theft Auto and Final Fantasy series, the latest two Metal Gear titles, all three Devil May Cry titles, and first-party Sony Computer Entertainment brands such as Gran Turismo, Ratchet & Clank' and Jak series.
The PS2 can read and play both compact discs and DVDs, making it backwards compatible with older PlayStation (PS1) games and allowing for playback of DVD Video and the more technically advanced PS2 games on either cheaper, smaller CD-ROM format or the larger, more expensive DVD-ROM format. The ability to play DVD movies allowed consumers to more easily justify the PS2's relatively high price tag (in October 2000, the MSRP was $300) as it removed the need to buy an external DVD player. The PS2 also supports PS1 memory cards (for PS1 game saves only) and joypads (the PS2's Dual Shock 2 controller is essentially a slightly upgraded PS1 Dual Shock).
When it was released, the PS2 had many advanced features that were not present in other contemporary video game consoles, including its DVD capabilities and USB and IEEE 1394 expansion ports. It was not until late 2001 that the Microsoft Xbox became the second console with (non-standard) USB and DVD support (this is assuming the Nuon, an advanced DVD player graphics coprocessor, is not considered a console).
Support for original PlayStation games was also an important selling point for the PS2, letting owners of an older system upgrade to the PlayStation 2 and keep their old software, and giving new users access to older games until a larger library was developed for the new system. As an added bonus, the PS2 had the ability to enhance PlayStation games by speeding up disc read time and/or adding texture smoothing to improve graphics. While the texture smoothing was universally effective (albeit with odd effects where transparent textures are used), faster disk reading could cause some games to fail to load or play correctly.
A handful of PlayStation titles (notably Metal Gear Solid: Special Missions) fail to run on the PS2 at all (Special Missions fails to recognise Metal Gear Solid at the disk swap screen, for example). It is a common misconception that disk swapping in a game (for example, for multi-disk games or expansion packs) is not possible on the PS2. The anomalous failure of the above title at its disk swap screen may have given birth to this rumor.
Software for all PlayStation consoles contains one of three region codes: for Japan, North and South America, or Europe. Discs also deviate slightly from the CD-ROM and DVD-ROM standards in ways that make it difficult for consumers to duplicate discs or create their own software for the system.
With the purchase of a separate unit called the Network Adaptor (which is built into the newest system revision), some PS2 games support online multiplayer. Instead of having a unified, subscription-based online service like Xbox Live, online multiplayer on the PS2 is free, but split between publishers. For example, all of Sony's games use a free service called PS2Online, all of Ubisoft's games use the ubi.com service, and so on.
Sony released a version of the Linux operating system for the PS2 in a package that also includes a keyboard, mouse, Ethernet adapter and hard disk drive. Currently, Sony's online store states that the Linux kit is no longer for sale in North America. However as of November 2004, the European version was still available. (The kit boots by installing a proprietary interface, the RTE (run time environment) which is on a region-coded DVD, so the European and USA kits each only work with a PS2 from that region).
In Europe and Australia, the PlayStation 2 comes with a free Yabasic interpreter on the bundled demo disk. This allows simple programs to be created for the PlayStation 2 by the end-user. This was included in a failed attempt to circumvent a UK tax by defining the console as a "computer" if it contained certain software.
The PlayStation 2 has undergone many revisions, some only of internal construction and others with substantial external changes. These are colloquially known amongst PlayStation 2 hardware hackers as V0, V1, V2, etc., up to V12 (as of November 25, 2004).
V0 was a Japanese model and were never sold in Europe or the US. These included a PCMCIA slot instead of the Expansion Bay (DEV9) port of newer models. V0 did not have a built-in DVD player and instead relied on an encrypted player that was copied to a memory card from an included CD-ROM (normally, the PS2 will only execute encrypted software from its memory card, but see PS2 Independence Exploit). V3 has a substantially different internal structure from the subsequent revisions, featuring several interconnected printed circuit boards. As of V4 everything was unified into one board, except the power supply. V5 introduces minor internal changes and the only difference between V6 (sometimes called V5.1) and V5 is the orientation of the Power/Reset switch board connector, which was reversed to prevent the use of no-solder modchips. V7 and V8 are also similar, and V9 (model number SCPH-50000/SCPH-50001) added the Infrared port for the optional DVD Remote Control, removed the widely unused IEEE 1394 port, added the capability to read DVD-RW discs, and a quieter fan. V10 and V11 have minor changes.
In September 2004 Sony unveiled the third major hardware revision (V12, model number SCPH-70000). Available in November 2004, it is smaller and thinner than the old version and includes a built-in Ethernet port. In some markets it also integrates a modem. Due to its thinner profile, it does not contain the 3.5" expansion bay, and therefore does not support the internal hard disk drive. This poses a problem for games such as Final Fantasy XI, which requires the use of this peripheral. It is widely believed that Sony has abandoned support for the hard drive. There are also some disputes on the numbering for this PS2 version, since there are actually two sub-versions of the SCPH-70000. One of them includes the old EE and GS chips, and the other contains the newer unified EE+GS chip, otherwise being identical. Since the V12 version had already been established for this model, there were some disputes regarding these sub-versions. Two propositions were to name the old model (EE and GS, separate chips) V11.5 and the newer model V12, and to name the old model V12 and the newer model V13. Currently, most people just use V12 for both models, or V12 for the old model and V13 for the newer one.
The redesigned system's release was timed to coincide with the much anticipated Grand Theft Auto: San Andreas, which was the highest selling game during the 2004 Holiday season. Sony stopped making the older PS2 model sometime during the summer of 2004 to let the distribution channel empty out stock of the units. After an apparent manufacturing issue caused some initial slowdown in producing the new unit, Sony reportedly underestimated demand, caused in part by shortages between the time the old units were cleared out and the new units were ready. This led to further shortages, and the issue was compounded in Britain when a Russian oil tanker became stuck in the Suez Canal, blocking a ship from China carrying PS2s bound for the UK. During one week in November, sales in the entire country of Britain totalled 6,000 units - compared to 70,000 a few weeks prior.  Shortages in the US were also extremely severe; one retail chain in the US, GameStop, had just 186 PS2 and Xbox units on hand across more than 1700 stores on the day before Christmas. 
Sony has also made a PVR/DVD burning consumer device that plays PlayStation 2 games called the PSX. The device was poorly received, with some major features absent from the first revisions of the hardware, and has thus far experienced very poor sales in Japan, in spite of major price drops . The machine's future continues to be uncertain, with North American and European launches considered to be distant if at all.
Main article: PlayStation 3
The successor to the PS2 is currently being developed, and is known as the PlayStation 3. There are very few confirmed facts at this point; however, Sony plans on releasing more information on the PlayStation 3 in spring of 2005, probably at the E3 trade show. What is known, is that PlayStation 3 will be backwards compatible, will use Blu Ray Technology, and its CPU will be a technology codeveloped by Sony, Toshiba, and IBM called the Cell.
Main article: PlayStation 2 peripherals
The PS2's controller is largely identical to the PlayStation's, with the same basic functionality; however, it includes analog pressure sensitivity on the face and shoulder buttons, is lighter and includes two more levels of vibration.
Optional hardware include additional controllers, a DVD remote control, a hard drive and modem, ethernet adapter, memory cards, and various cables and interconnects.
The specifications of the PlayStation 2 console are as follows, with hardware revisions:
- CPU: 128 bit "Emotion Engine" clocked at 294 MHz (later versions 299 MHz)
- System Memory: 32 MB Direct Rambus or RDRAM (note that some computers use this type of RAM)
- Memory Bus Bandwidth: 3.2 GB per second
- Main processor: MIPS R5900 CPU core, 64 bit
- Co-Processor: FPU (Floating Point Multiply Accumulator × 1, Floating Point Divider × 1)
- Vector Units: VU0 and VU1 (Floating Point Multiply Accumulator × 9, Floating Point Divider × 1), 128 bit
- Floating Point Performance: 6.2 GFLOPS
- 3D CG Geometric Transformation: 66 million polygons per second (1)
- Compressed Image Decoder: MPEG-2
- I/O Processor interconnection: Remote Procedure Call over a serial link, DMA controller for bulk transfer
- Graphics: "Graphics Synthesizer" clocked at 150 MHz
- DRAM Bus bandwidth: 48.0GB per second
- DRAM Bus width: 2560 bits
- Pixel Configuration: RGB:Alpha:Z Buffer (24:8, 15:1 for RGB, 16, 24, or 32-bit Z buffer)
- Maximum Polygon Rate: 75 million polygons per second (1)
- Dedicated connection to: Main CPU and VU1
- Sound: "SPU1+SPU2"
- Number of voices: 48 hardware channels of ADPCM on SPU2 plus software-mixed channels
- Sampling Frequency: 44.1 kHz or 48 kHz (selectable)
- I/O Processor
- CPU Core: Original PlayStation CPU (MIPS R3000A clocked at 33.8 MHz or 37.5 MHz)
- Sub Bus: 32 Bit
- Connection to: SPU and CD/DVD controller.
- Interface Types: 2 proprietary PlayStation controller ports, 2 proprietary Memory Card slots using MagicGate encryption, Expansion Bay (DEV9 or PCMCIA on early models) port for Network Adaptor, Modem and Hard Disk Drive, IEEE 1394 (2), Infrared remote control port (2), and 2 USB 1.1 ports with an OHCI-compatible controller.
- Disc Media: DVD-ROM (CD-ROM compatible) with copy protection. 4.7GB capacity, a few are DVD-9 (8.5 GB)
(1) Polygons per second under ideal circumstances (e.g. no texturing, lighting, or vertex colors applied). Some criticize these figures for being unrealistic, and not indicative of real-world performance. The true polygons per second figure with full textures, effects etc. is around 13 million.
(2) IEEE 1394 removed in SCPH-50000 and later hardware versions, and Infrared remote port added.