Where does the arrow or other such pointer controlled by the mouse on the PC monitor exist? The image is formed by charged particles colliding with some phosfluerescent substance on the screen (or, at least CRTs do). But, where is the mouse pointer? Is it a real object or virtual? Why doesn’t it interfere with how a CRT works? For extra credit, feel free to explain how flat screens form images, and where the mouse is there, too…
The mouse pointer is just an image, just like any other image. It is drawn at the desired coordinates, “on top” of everything else on the screen. The coordinates come from the current mouse position. In modern computers, the video card might do the calculations necessary to keep the pointer from erasing what was below it when it’s moved, but in old systems, the CPU had to keep track of the pixels under the pointer, and put them back when it moved.
“Flat screens” (LCDs) take the same video data that CRTs do, the image is simply formed by tiny shutters made from liquid crystals that open and close rapidly, allowing colored light to shine through. The colored light is usually white light that is filtered under each sub-pixel as Red, Green, or Blue.
There’s plenty of information about this on the web: Liquid-crystal display - Wikipedia
The pointer a small magnetic object moved by a series of arms behind the screen of the CRT. The arms are manipulated by 2 to 4 hamsters running on wheels, who respond according to where you place a small piece of carrot using the external mouse control. In LCD monitors, the hamsters are very flat.
In all seriousness, though, I don’t understand your question. The pointer is an image. It is generated by the video card and displayed on the screen. Just like everything else on the screen.
The mouse is the physical object in your hand. The pointer is just data.
Yes. It is the manifestation, on this sub-plane of reality, of the hyper-intelligent, pan-dimensional being that created your computer.
Yes…and reality is just a pigment of my colorful imagination! 
With this - you win your own thread! :eek:
Does the mouse exist? Well, set Schrödinger’s cat to catching it – if it does. 
A monitor is composed of small, colored dots (aka: pixels) that emit light. The images on your monitor are created from your video card, which is drawing the data from your CPU. To give the illusion of motion, your monitor cycles (or refreshes) the images on your screen many times a second (known as Hertz). When you move your mouse, the arrow-pointer is simply just another graphic that is constantly redrawn, pixel by pixel, from the video card to correspond with your hand/mouse movement.
So, in essence, it’s a 2D pattern of light.
I suspect part of the confusion here is that on wintel computers, the mouse cursor seems to enjoy an existence somewhat immune from the operation of the OS - when the system is very busy, everything may go very laggy, or may freeze (or crash), but the mouse cursor (often, not always) will still move as normal.
I believe this is because it has its own interrupt process - it still gets a slice of processor time, regardless of whatever else may be happening.
Computer mouse-ish stuff starts with the hardware in your hand. In ye olde days of computers, a mouse was simply a trackball that had been turned upside down. It had two wheels, one in the vertical direction and one in the horizontal direction. Each wheel had two sets of slots in it. An infra-red LED was on one side of the slots, and a photodetector of some sort (photodiode or phototransistor) was on the other side. A microcontroller simply monitored the output of the photodetector, and by doing so could tell when a slot passed by the LED/photodetector pair. By simply counting how many times the beam was broken and re-established, the microcontroller could tell how far the mouse was moved. Two rows of slots, each slightly offset from each other were needed so that the direction of movement could also be known.
The smallest amount of movement that could be detected was the distance that the mouse ball would roll between two consecutive slots in the wheels. This smallest unit of mouse movement counts is called the “Mickey”, and it is named after Mickey Mouse. No, I’m not kidding.
Periodically, the mouse would send the total of counts (positive or negative depending on the direction) as well as the state of the mouse buttons and would transmit it to the computer, either through the PS/2 port or the serial port, depending on which type of mouse that you had. This triggered an interrupt, which was serviced by the operating system’s mouse interrupt handler. The computer’s operating system would take these counts and would increment or decrement its X and Y coordinates for the mouse pointer accordingly.
A modern mouse uses optics to determine how far the mouse moves, and usually has a USB interface instead of PS/2 or RS-232, but the basic principle of operation is the same. The USB mouse still sends counts back to the computer. This generates an interrupt and the USB device handler manages the coordinates for the mouse pointer.
The computer keeps the display data in an array of numbers. At some point (which varies a bit depending on what operating system is involved) a graphical image corresponding to the mouse pointer is written into the appropriate locations in this data array. At this point, the “mouse pointer” is just numbers in an array, mixed in with all of the other numbers in the array that make up the display data. The mouse pointer is no longer a unique entity. It is just part of the screen data. It may look to the user like it rides on top of the screen data, but in reality it doesn’t. It just gets copied onto the screen data last so that it always looks like it is on top.
This display data is then sent to the video card, where it is displayed on the screen. In an old fashioned analog monitor, the data is converted into analog signals corresponding to the three primary colors that the monitor uses, which are red, green, and blue (hence they are called RGB monitors). The monitor starts in the upper left hand corner of the screen, and just starts running through the data. A higher “number” in that pixel location corresponds to a higher signal level in the RGB signals, and the monitor simply scans from left to right, then drops down a line and scans left to right, and so forth until it reaches the end of the screen, at which point it jumps back up to the upper left and starts over again. “Line sync” and “screen sync” signals generated by the video card control when the monitor jumps down to the next line and when it starts back on the upper left corner. The stronger the electron beam at any given point, the brighter that color appears at that point. The phosphor on the monitor’s surface holds that color long enough that your eyes can detect it, but it fades out before the next sweep of the electron beam.
In a modern monitor, the digital data is sent directly to the monitor, so there is no loss of information like there is in the conversion to an analog signal in an older CRT type monitor. Instead of an electron beam, electricity is applied to liquid crystals in an array, which determines whether that dot is “on” or “off”. Light is shone into the back of the crystals, and the state of the crystal determines whether or not that light passes through the crystal and is visible or not.
Actually, I think the cursor may be more real than we know… :eek:
Pretty much. Every time the mouse moves a preset interval an “event” is generated on the IO bus. The IO bus then generates an interrupt which causes the OS to save the context associated with the currently executing process and then turn over control to software which knows how to interpret the event. That software then queues a process that further processes the event by doing things like redrawing the mouse pointer in a new position. The process associated with processing IO events typically run at a higher priority than other processes, which is why you can still see the mouse pointer move when everything else is sluggish. It’s amazing that the OS can run at all when it is being interrupted so often.