What is this Connector?

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What is this Connector?
It’s probably a dumb question to ask, but what is this Connector (4-Pin) on the Apple I Motherboard? And what does the Dot with the J2 under it mean? The 4-Pin Connector can also be seen on the Prototype Motherboard but without the Dot with the J2 under it. (Please Note I do not own a Apple I, I’m just very interested in it. And I do not know a lot about old PCs.)
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Video connector

The four-pin connector carries composite video from the Apple I to a television or monitor. Only two of the pins are used: video and ground. "J2" is the designation for this part on the silk screen layer. It is numbered that way because it is one of only three positions where connectors are soldered into the board, the others being the power connector J1 and the bus connector J3, usually used for the cassette interface. "J" is the way female connectors are usually designated on printed circuits. It stands for "jack". A male connector would be designated with a "P" for "plug".

 

The dot you mentioned is a mounting hole to screw the board into a case.

 

The prototype was made without a solder mask or silk screen layer, as those additional fabrication steps would add significantly to the cost when only one or two units were being made. Same for the mounting holes, which needed to be drilled using special tools at the printed circuit factory, so they were also omitted.

 

There are quite a few questions surrounding this prototype, including how it was broken—accident or deliberate?— and why the corners were cut off.

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Thank you very much! That's

Thank you very much! That's all the Information I needed (very detailed).

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