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.
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.
Since the V12 version had already been established for this model, there were some disputes regarding these sub-versions.
When the PlayStation 2 launched in America in October 26, 2000, Sony sold 510,000 units within the first 24 hours.
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.
V3 has a substantially different internal structure from the subsequent revisions, featuring several interconnected printed circuit boards.
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.
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.