Quantum Link (or Q-Link) was a U.S. and Canadian online service for Commodore 64 and 128 personal computers that operated from November 5, 1985 to November 1, 1995. It was operated by Quantum Computer Services of Vienna, Virginia. In October 1991 they changed the name to America Online, which continues to operate the AOL service for the IBM PC and Apple Macintosh today. Q-Link was a modified version of the PlayNET system, which Control Video Corporation (CVC, later renamed Quantum Computer Services) licensed.
Q-Link featured electronic mail, online chat (in its People Connection department), public domain file sharing libraries, online news, and instant messaging (using On Line Messages, or OLMs). Other noteworthy features included online multiplayer games like checkers, chess, backgammon, hangman and a clone of the television game show "Wheel Of Fortune" called 'Puzzler'; and an interactive graphic resort island called Habitat while in beta-testing and later renamed to Club Caribe.
In October, 1986 QuantumLink expanded its services to include casino games such as bingo, slot machines, blackjack and poker in RabbitJack's Casino and RockLink, a section about rock music. The software archives were also organized into hierarchal folders and were expanded at this time.
Club Caribe was developed with Lucasfilm Games. It was designed using software that would later form the basis of Lucasfilm's Maniac Mansion story system (SCUMM). Users controlled on-screen avatars that could chat with other users, carry and use objects and money (called tokens), and travel around the island one screen at a time. It was a predecessor to today's MMOGs.
Connections to Q-Link were typically made by modems with speeds from 300-2400 baud, with 1200 baud being the most common. The service was normally open weekday evenings and all day on weekends. Pricing was $9.95 per month, with additional fees of six cents per minute (later raised to eight) for so-called "plus" areas, which included most of the aforementioned services. Users were given one free hour of "plus" usage per month. Hosts of forums and trivia games could also earn additional free plus time.
The system competed with other online services like CompuServe and The Source, as well as Bulletin board systems (single or multiuser), including gaming systems such as Scepter of Goth and Swords of Chaos. Quantum Link's graphic display was better than many competing systems because it used specialized client software with a nonstandard protocol. However, this specialized software and nonstandard protocol also limited its market, because only the Commdore 64 and 128 could run the software necessary to access Quantum Link.
In the summer of 2005, Commodore hobbyists reverse engineered the service, allowing them to create a Q-Link protocol compatible clone called Quantum Link Reloaded which runs via the Internet as opposed to telephone lines. Using the original Q-Link software as a D-64 file, it can be accessed using either the VICE Commodore 64 emulator (available on multiple platforms, including Windows and Linux), or by using authentic Commodore hardware connected to the Internet by way of a serial cable connected to a PC with internet access.
See also 
- Q-Link Promotion Video from 1986
- Quantum Link Reloaded
- Remember Q-Link
- JohnD39's Q-Link contact/memories site