Update

digital.md

@@ -8,7 +8,9 @@ Normies confuse digital with [electronic](electronic.md) or think that digital c
 
 The advantage of digital technology is its **resilience to [noise](noise.md)** which prevents degradation of data and accumulation of error -- if a digital picture is copied a billion times, it will very likely remain unchanged, whereas performing the same operation with analog picture would probably erase most of the information it bears due to loss of quality in each copy. Digital technology also makes it easy and practically possible to create fully programmable general purpose [computers](computer.md) of great complexity.
 
-**Digital vs analog, simple example:** imagine you draw two pictures with a pencil: one in a normal fashion on a normal paper, the other one on a grid paper, by filling specific squares black (making kind of manual [pixelart](pixelart.md)). The first picture is analog, i.e. it records continuous curves and position of each point of these curves can be measured down to extremely small fractions of millimeters -- the advantage is that you are not limited by any grid and can draw any shape at any position on the paper, make any wild curves with very fine details, theoretically even microscopic ones, you have [infinite](infinity.md) space of possibilities at your disposal. The other picture (on a square grid) is digital, it is composed of separate points whose position is described only by whole numbers (*x* and *y* coordinates of the filled grid squares), the disadvantage is that you are limited by only being able to fill squares on predefined positions so your picture will look blocky and limited in amount of detail it can capture (anything smaller than a single grid square can't be captured properly), the [resolution](resolution.md) of the grid is limited as well as the number of possible pictures you can draw this way, but as we'll see, imposing this limitations has advantages. Consider e.g. the advantage of the grid paper image with regards to copying: if someone wants to copy your grid paper image, it will be relatively easy and he can copy it exactly, simply by filling the exact same squares you have filled -- small errors and noise such as imperfectly filled squares can be detected and corrected thanks to the fact that we have limited ourselves with the grid, we know that even if some square is not filled perfectly, it was probably meant to be filled and we can eliminate this kind of noise in the copy. This way we can copy the grid paper image a million times and it won't change. On the other hand the normal, non-grid image will become distorted with every copy and in fact even the original image will become distorted by aging; even if that who is copying the image tries to trace it extremely precisely, small errors will appear and these errors will accumulate in further copies, and any noise that appears in the image or in the copies is a problem because we don't know if it really is a noise or something that was meant to be in the image.
+A **typical example** of analog versus digital technology is wrist watches: analog ones have rotating hands to show time, digital ones use digits -- note that it doesn't matter if is the watch is electronic or not, the distinction is in how time is shown. A hand rotates continuously, it may be positioned at any arbitrary angle, basically with "infinite resolution", whereas digits are discrete, non-continuous -- a digit will instantly switch to being a different digit. This is the distinction between analog and digital.
+
+**Another simple example:** imagine you draw two pictures with a pencil: one in a normal fashion on a normal paper, the other one on a grid paper, by filling specific squares black (making kind of manual [pixelart](pixelart.md)). The first picture is analog, i.e. it records continuous curves and position of each point of these curves can be measured down to extremely small fractions of millimeters -- the advantage is that you are not limited by any grid and can draw any shape at any position on the paper, make any wild curves with very fine details, theoretically even microscopic ones, you have [infinite](infinity.md) space of possibilities at your disposal. The other picture (on a square grid) is digital, it is composed of separate points whose position is described only by whole numbers (*x* and *y* coordinates of the filled grid squares), the disadvantage is that you are limited by only being able to fill squares on predefined positions so your picture will look blocky and limited in amount of detail it can capture (anything smaller than a single grid square can't be captured properly), the [resolution](resolution.md) of the grid is limited as well as the number of possible pictures you can draw this way, but as we'll see, imposing this limitations has advantages. Consider e.g. the advantage of the grid paper image with regards to copying: if someone wants to copy your grid paper image, it will be relatively easy and he can copy it exactly, simply by filling the exact same squares you have filled -- small errors and noise such as imperfectly filled squares can be detected and corrected thanks to the fact that we have limited ourselves with the grid, we know that even if some square is not filled perfectly, it was probably meant to be filled and we can eliminate this kind of noise in the copy. This way we can copy the grid paper image a million times and it won't change. On the other hand the normal, non-grid image will become distorted with every copy and in fact even the original image will become distorted by aging; even if that who is copying the image tries to trace it extremely precisely, small errors will appear and these errors will accumulate in further copies, and any noise that appears in the image or in the copies is a problem because we don't know if it really is a noise or something that was meant to be in the image.
 
 But this is not to say digital data can't become distorted too -- it can. It is just less likely and it's easier to deal with this. It for example happens that space particles (and similar physics phenomena, e.g. electronic interference) flip bits in computer memory, i.e. there is always a probability of some [bit](bit.md) flipping from 0 to 1 or vice versa. We call this **data [corruption](corruption.md)**. This may also happen due to physical damage to digital media (e.g. scratches on the surface of CDs), imperfections in computer network transmissions (e.g. packet loss over [wifi](wifi.md)) etc. However we can introduce further measures to prevent, detect and correct data corruption, e.g. by keeping [redundant](redundancy.md) copies (2 copies of data allow detecting corruption, 3 copies allow even its correction), keeping [checksums](checksum.md) or [hashes](hash.md) (which allow only detection of corruption but don't take much extra space), employing error correcting codes etc. We have to keep in mind that data corruption is very dangerous because a small local damage may destroy the whole data (owing partially to our wrong assumption that digital data data won't be damaged), while local damage to analog data will typically only destroys that one small affected part, keeping the rest intact. So let's be aware of this.