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16 - BUS In the real world, a given computer is actually a number of components each with their own "CPUs." Sometimes these components are built into the same chip, sometimes they are not. Something else you may wish to do is send multible bytes of data over one wire, instead of many, many wires. This is possible, but it is slower. Remember how a RAM MCU worked with a "CLOCK pin?" The idea is, you can use a demultiplexer to address individual bits of a byte. Now, if you use a multiplexer on 8 lines to get 1 line, then you use a demultiplexer to take that 1 line and turn it back into 8, you merely have to syncronize the "selector" of the multiplexer, and couple it with a "clock pin" so that things don't change when set to 0 (which helps reliability alot, especially when a new bit could go on or off before the multiplexer has changed it's selection). This is called a "serial bus," as opposed to a "parallel bus." The advantage of this is fewer wires crossing each other, and it allows for fewer pins (the things that stick out on a chip if you haven't guessed that already). The disadvantage is that it is much, much slower, and it can take a few extra pins to get working. However, if you establish a "communication protocol" or standard that every piece of equipment listens to, you can mitigate this and allow, easily, 256 different pieces of equipment to talk over 2 wires (data and clock), or even 1 wire (if everyone runs on the same calibrated clock rate), if you're limiting yourself to 8 bits. Sure, it's slow, but that slow is still faster than a human can perceive it. There are some well known standards out there that you can look into, like I2C, RS232, USB (Universal Serial Bus) and so forth.

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