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 FireWire port, added the capability to read DVD-RW discs, and a quieter fan.
It also has a different lens and some compatibility issues documented by Sony for earlier PS2 games.
It is widely believed that Sony has abandoned support for the hard drive.
Only a few million users had obtained consoles by the end of 2000 due to manufacturing delays.
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.
These included a PCMCIA slot instead of the Expansion Bay (DEV9) port of newer models.
The PS2 also supports PS1 memory cards (for PS1 game saves only) and controllers (the PS2's Dual Shock 2 controller is essentially a slightly upgraded PS1 Dual Shock).
Although Sony placed little emphasis on online gaming during its first year, all that changed because of the launch of the online-capable Xbox.
Developers also complained that it was difficult to develop for the system, with little in the way of reference material from Sony for its exotic architecture.
In September 2004 Sony unveiled the third major hardware revision (V12, model number SCPH-70000).
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.
