Falk Joensson's
Learning Programming with Eas
(Easy Application Script Tutorial)

How the Computer Works:06. Step by Step

The core of the computer (or microcontroller) is the central processing unit, CPU. This is where the real magic happens. The states (bits) of all input, output and control lines are held here in extra flip-flops, called registers. The pivotal register is the program pointer. When you turn on the computer, it starts with the value "0" and is increased by 1 on every tick of a clock. This clock is a quartz crystal oscillator, just like in a wrist watch, only much faster. A 16 MHz clock ticks 16 million times each second, a 2 GHz clock 2 billion times each second, to give two examples (microcontroller vs PC). A quartz crystal in an electric circuit resonates with a very reliable frequency that is used to trigger reading and writing cycles in the CPU, including increasing the program pointer. The program pointer is an address for the program memory, so as it starts with 0, the program memory data at address 0 is the first "line of code" executed. On the next tick of the computer clock, the program pointer becomes 1, and the second "line of code" gets executed, and so on.
06. Step by Step
T Two Things You Need
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