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The data bus (green) and the address bus (yellow) wired. The data bus allows bytes transfered between the processor, the ROM and the RAM. The data byte consists of 8 bits, 8 wires carrying a bit each. The address bus allows the processor to chose data storage slots in the memory (RAM and ROM) for bytes to store or load. The address byte is 16 bits wide.
Wire wrapping is an old craft from the 1960-70’s. The idea is that a piece of wire is wrapped tight around square shaped pots protruding from the board. The blue tool shown in the previous post exerts tons of force per square inch that creates molecular bond between two pieces of unoxidised metal. Thus the wire wrapped connection is very reliable and gas tight. According to old electronic engineers wire wrapping can be 100% reliable if done properly. Also, since the wire is wrapped 7-8 times around the post, it offers greater surface are for contact, as opposed to soldering. Computers, including the Apollo Guidance Computer used for lunar landing and many space probes from the 60’s and 70’s were made with wire wrapping. This is the backplane of a PDP-8 computer from the 70’s.

PDP-8 backplane

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