Editing Atari 8-bit computers (section)

=== FCC issues ===

Televisions of the time normally had only one signal input, which was the antenna connection on the back. For devices like a computer, the video is generated and then sent to an [[RF modulator]] to convert it to antenna-like output. The introduction of many game consoles during this era had led to situations where poorly designed modulators would generate so much signal as to cause interference with other nearby televisions, even in neighboring houses. In response to complaints, the [[Federal Communications Commission]] (FCC) introduced new testing standards which are extremely exacting and difficult to meet.{{sfn|Goldberg|Vendel|2012|p=466}}

Other systems avoided the problem by using built-in composite monitors, such as the PET and TRS-80. The TRS-80 has a slightly modified black and white television as a monitor. It was notorious for causing interference, and production was canceled when the more stringent FCC requirements came into effect on January 1, 1981. [[Apple Computer]] left off the modulator and sold them under a third party company as the [[Sup'R'Mod]] so they did not have to be tested.<ref>{{cite web |title=3-The Apple II |url=https://apple2history.org/history/ah03/ |website=Apple II History|date=November 30, 2008 }}</ref>

In a July 1977 visit with the engineering staff, a [[Texas Instruments]] salesman presented a new possibility in the form of an inexpensive [[fiber-optic cable]] with built-in [[transceiver]]s. During the meeting, [[Joe Decuir]] proposed placing an RF modulator on one end, thereby completely isolating any electrical signals so that the computer would have no RF components. This would mean the computer would not have to meet the FCC requirements, yet users could still attach a television simply by plugging it in. His manager, Wade Tuma, later refused the idea saying "The FCC would never let us get away with that stunt." Unknown to Atari, TI used Decuir's idea. As Tuma had predicted, the FCC rejected the design, delaying that machine's release. Texas Instruments shipped early machines with a custom television as the testing process dragged on.{{sfn|Goldberg|Vendel|2012|p=466}}

To meet the off-the-shelf requirement while including internal TV circuitry, both new machines were built around cast aluminum shields forming a partial [[Faraday cage]], with the various components screwed down onto this internal framework. This resulted in a sturdy computer, at the disadvantage of added manufacturing expense and complexity.<ref name=atarihistory/>

The FCC ruling also made it difficult to have any sizable holes in the case, which would allow RF leakage. This eliminated expansion slots or cards that communicated with the outside world via their own connectors. Instead, Atari designed the [[Atari SIO|Serial Input/Output]] (SIO) [[Bus (computing)|computer bus]], a system for daisy-chaining multiple, auto-configuring devices to the computer through a single shielded connector. The internal slots were reserved for ROM and RAM modules; they did not have the control lines necessary for a fully functional expansion card, nor room to route a cable outside the case to communicate with external devices.<ref name=atarihistory/>