The level of popularity this system achieved during the noughties is unprecedented; by the end of its lifespan in 2013 (after 13 years!) its game library boasted 1,850 titles .
Mr Moskeeto (2001). Whenever someone argues about the abundance of PS2 games, I remember this one.
What happened here is really impressive. The PS2 did not possess a 'programmer-friendly' architecture (as seen from the perspective of a PC programmer). Yet, given the vast number of games developed for it, I too wonder if other factors were involved, such as favourable licensing terms, low development and distribution costs, its compact form factor, and whatnot.
Having said that, let's examine the PlayStation 2 as a development platform; maybe this will help us understand more.
Development ecosystem
Sony provided both hardware and software to assist game development.
On the software side, the PlayStation 2 SDK included :
- The Emotion Engine toolchain: A set of C and C++ compilers, assemblers, linkers, and debuggers used to control each element of the EE. The main CPU was mainly programmed using C/C++; however, performance-critical components like the vector units were instead programmed using assembly (for writing microcode and/or macrocode).
- The kit also included an 'Emotion Engine simulator' for preliminary code testing without deploying it on the real hardware, although the simulator wasn't as accurate as the physical EE chip.
- All these tools worked on Linux, Solaris, and Windows. The latter variant ran within the Cygwin environment.
- Low-level libraries: Intended for interfacing many system functions (using BIOS calls).
- Analysis tools to profile performance and resource usage.
- Support applications to communicate with the official development hardware.
On the hardware side, Sony provided studios with dedicated equipment to run and debug games in-house. The initial devkits were bare boards stacked together to replicate the unreleased PS2. Later kits (named Development Tool) featured a more presentable appearance and enhanced I/O. The tower integrated workstation hardware (running RedHat 5.2) with PS2 internals to build and run the game from a single unit .
The combination of the devkit, the official SDK, and CodeWarrior (a famous IDE) constituted one of the most popular setups.
The new medium
The disc drive is certainly one of the crown jewels of this console, while competitors hit-and-missed with formats that didn't catch attention outside game shelves. Sony's bet on the Digital Video Disc (DVD) paid off as soon as movie studios began shipping their films in plastic cases. Thus, consumers were drawn to buying a PlayStation 2 even if video games were not their main appeal.
Kingdom Hearts II (2005). Typical retail game box and disc.
So, what's a DVD anyway? It's the major successor to the Compact Disc, and a result of extensive arguing between major manufacturers until they finally compromised on a common standard.
Inside the DVD
The DVD inherits the CD's form factor but incorporates key differences that make it exponentially more useful and reliable.
First of all, the reading equipment requires a more sophisticated lens capable of resolving finer detail. It does so by housing a higher numerical aperture and a laser that produces a 650 nm wavelength (within the red spectrum) . Compared to the 780 nm wavelength (near-infrared) that the CD relied upon, the DVD can condense more pits and lands to pack more information.
However, as the recorded bits become smaller, the system also becomes more sensitive to defects. Therefore, the new medium instead employs Reed-Solomon Product-Code (RS-PC) for error correction and 8-to-16 modulation for encoding data into pits and lands. Without diving into the details, both methods increase overhead in exchange for greater reliability.
As a result, a typical DVD, called DVD-5, can hold up to 4.7 GB of data. Nonetheless, the disc also supports dual layer recording, in which two data layers sit at different depths; the laser then refocuses to read one or the other. This leads to the DVD-9 variant, allowing up to 8.54 GB of storage (albeit less common for PS2 games) . Finally, there's a third format, DVD-10, which uses a single layer on both sides of the disc (similar to vinyls and LaserDiscs), but I'm not aware of any commercial game ever using it.
In any case, the PS2 drive housed two laser diodes, supporting both CDs and DVDs. So, games had a choice of either format, with developers, over time, favouring the latter one.
A long-term spec
Unlike the original CD audio, which subsequently evolved into the CD-ROM, CD-ROM XA, and more variants as needs emerged, the DVD is a unified format designed to store data using a standardised file system, typically the Universal Disk Format (UDF) .
Consequently, the medium supported games and movies from the get-go. That said, DVD movies adhere to a common structure called DVD-Video, which accommodates MPEG2 video, audio, interactive navigation, and copy protection. The PS2 was well-equipped for this task thanks to the IPU and SPU, but it still needed a 'DVD player' software to understand DVD-Video data. Sony, for some reason, didn't implement one in the initial PS2 revision; instead, a Utility Disc was supplied within the box, which installed a player onto the Memory Card . From revision SCPH-18000 (2000) onwards, the DVD playback software always came pre-installed in the BIOS ROM.
Speaking of DVD movies, you may be curious to know that the format also adopted a resolution of 720 × 480 (NTSC) or 720 × 576 (PAL), the same dimensions as Digital Television (DTV). These were selected to properly support anamorphic widescreen on contemporary televisions .
Network service
While Sega heavily marketed the Dreamcast around online services (even before they were ready), Sony initially left it to third parties to supply both the hardware and the Internet Service Provider (ISP) access. The hardware eventually appeared in the form of USB modems . It wasn't until a year later, in 2001, that Sony released the first-party accessory known as the Network Adaptor, providing both modem and Ethernet connectivity , followed by the PSBBN interface to make proper use of it. However, the latter only landed in Japan.
Similarly, game studios were in charge of providing the necessary infrastructure if they decided to provide online services (such as multiplayer). In later years, Sony deployed the Dynamic Network Authentication System or 'DNAS' . Unlike Xbox Live, it was just an authentication system to prevent pirated games from connecting online.
An unusual kind of game
Apart from all these games with their fancy triangles, Sony also shipped a Linux distribution based on 'Kondara' (which is in turn based on Red Hat 6) in the form of two DVDs.
The first disc is called 'Runtime Environment' and the second 'Software Packages'. The package also came with an AV Multi Out to VGA adaptor, USB Keyboard and Mouse, plus some developer manuals.
This suite was known as Linux Kit and you would run the OS by booting from the first DVD, and then proceeding as with any old-school Linux environment. Users obviously needed a hard drive fitted to install the Linux distribution, and once done, the first DVD was always required for booting this OS.
Linux Kit included Kernel 2.2.1, compilers targeting the EE (gcc 2.95.2 with glibc 2.2.2), and assemblers targeting the vector units. There was also a window system (XFree86 3.3.6) 'accelerated' by the Graphics Synthesizer . Overall, I found this a very interesting platform. In fact, one of the research papers I consulted while writing this article was carried out using this setup.
With regards to the AV Multi Out to VGA adaptor, you may be interested to know that, while games diverged in aspect ratio, the Graphics Synthesizer supported the VESA standard, which unlike the DTV-VGA mix of the Dreamcast, used proper timings. Alas, the Multi Out's sync signal was supplied on the green channel... so I guess no one can be perfect. Anyway, VESA provided a resolution of up to 1280 x 1024 pixels, and I imagine Linux Kit was its main target.
Finally, it's worth noting that the futuristic PSBBN shell is based on PS2 Linux . Its bootloader launches a customised PS2 Linux Kernel and then loads the PSBBN graphical interface. This makes sense, as its multimedia-rich capabilities would otherwise have had to be implemented from scratch, although I wonder whether not talking to the native OS contributed to the one-minute boot times.