How do you go from some silicon wafer with some metallic lines printed on it to having a GUI desktop. I don’t understand the intersection between hardware and software at the fundamental level.
In: Technology
Let’s break this apart.
Computer processors are made from billions of tiny little switches called transistors. A transistor can be on or off. Conviently, we can base a maths system around this, a base-2 system. What that boils down to is that we can represent information by a series of on and/or off transistors. By arranging them in the right way, we can make the transistors store long pieces of information. This is your computer’s memory. The processor recieves a peice of information, and can do things to it. It can do arithmetic operations (add, subtract, multiply, and divide), logic operations (>, <, =), and others (register shifting, counting the 1’s or 0’s). So basically, the processor takes commands and information, and outputs information back to memory
When you initially turn on a computer, a bit of special memory is loaded into main memory and the processor runs it. This is the BIOS, or basic input-output system. It provides the necessary instructions to startup the hardware and put all the transistors in the right state. After this, your operating system is loaded into memory, and the processor begins to launch it.
To provide you with a GUI, the processor and software together are doing two things: 1) creating what is displayed and 2) talking to the monitor.
Lets start with 2. The monitor you use can vary, but the basic principle is the same. An array of tri-color lights are setup. Because of our eyes, a mix of mono-chromatic red green and blue light can create almost any color we can perceive. So for each point of 3 colors on the display, we can control the brightness of each light to control its effective color and brightness put a bunch together at a far distance and you brain blurs them into an image. So the monitor is designed to recieve a very specific set of information, the specific levels for each light across the array. This creates the image we see
1) The processor is the one producing this stream information. Let’s start basic, and say it’s only doing the background wallpaper. That image is stored in memory (stored in the same way the monitor will recreate it, as an array of rgb light), and the processor is taking each line of that image, and turning into the data stream it’s sending to the monitor. The processor also puts the mouse icon in a default position on the screen, and tracks the x and Y moments the mouse makes and recreates them on the screen. The software will command the processor that during a specific part of the stream for the screen, instead of the background, it’s going to make something new, a box with the start button in it. The processor knows the monitors resolution (because the monitor is also another computer that can talk to the big computer), so it knows how much space it’s working in. And when creating the stream for a particular x, y coordinate, it will make the box and button. It takes input from your mouse, and when you move the mouse to the same coordinates as the button and click, the processor recognizes the click in the right spot and executes the program associated with the button, according to its software. That’s how you interact with the screen in front of you.
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