Pixels (Manawatu) Mystery Cache
the Seagnoid: Stopped by to do some maintenance but I see the black pixel is no longer what it was, a nice cube of black. It has collapsed and is now more of a sprawl of black. No longer worthy so is archived. The cache has been removed.
-
Difficulty:
-
-
Terrain:
-
Size: 
(small)
Please note Use of geocaching.com services is subject to the terms and conditions
in our disclaimer.
A 101 lesson on how computer screens work.
If we think of a computer processor as a device that uses instructions to convert an input into some form of output, then computers have a number of processors in them. There is the central processor, the main one that we always think of in a computer. There is also the keyboard controller that sees a button pushed and hands on to the main processor that it was the letter "A". There is the hard disk controller that, on receiving a request from the central processor to retrieve some data from a part of the disk, moves the heads until the correct data is found. And there is the video controller that, on an instruction to draw a vertical line, translates that into the horizontal scan data that the monitor needs - draw a dot here... wait... wait... now another dot... wait... etc.
Okay, it is not really like that. How the video controller works is quite complex, and outside of the scope of this discussion. But eventually it converts the data to be displayed into a stream of colour bit information that is sent down the video cable to the monitor. Included in that data stream are two main instructions (there are others). One is the Vertical Sync. This commands the scan to start from the beginning again, from the top of the screen. Data will then be delivered to the screen telling each little picture element, each pixel, to light up a particular colour, until it gets to the right edge of the screen. Then a Horizontal Sync is sent - this tells the monitor to start the scan from the left hand edge again, but one row further down. The screen is again filled to the right edge one pixel at a time, then another Horizontal Sync, and so on, until the scan gets to the bottom right corner, when a Horizontal Sync moves the scan back to the left edge (and down one, so it will be off the bottom of the display), and a Vertical Sync moves it back to the top line to start a new screen. And all this happens at maybe 75 times a second. That's a lot of data to move!
It's worse than that. Each little pixel on the screen, the smallest unit the screen can display, is made of three colours, red, green and blue. These combine to give all the colours needed. For instance red and green make yellow (The pixels on a computer screen are rather small, on a TV they are bigger. Get right up to the screen, just an inch away, and you should be able to see that yellow is made with red and green). To get the various shades each of the three primary colours is comprised of 8-bit data, which allows for 256 shades of that colour. So each pixel has 3 x 8 data bits. (For the geeks amongst you, 24 bits per pixel, on a 1920 x 1080 display, which is two million pixels, at 75 times a second, requires a transfer speed of 3.7Gb/s! Wow!)
For our training example below we will assume just one bit per primary colour, making 3 bits per pixel. Either the colour is on or off. So...
000 = Black (all colours off)
001 = Red
010 = Green
100 = Blue
011 = Yellow (green + red)
101 = Magenta (blue + red)
110 = Cyan (blue + green)
111 = White (blue + green + red)
And here is the data streaming down the video cable to the monitor:
|HSync||VSync|00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000|HSync|0000000110110000000000000000100000001111110000
00001001001000000110110000000000100100000000000000000000100100000000000010000000000001000000000000010010010010
|HSync|00001100000001100000000001000000011100000011100000100000100011000000011000010000000010001101101101110000
0000100000010010000000001001000000000010010010010111|HSync|0000110000000000000000100000000001110000001110000010
01001000000000000110000000000011100011011011011100011011100000000010000000000001000000010010010010111111|HSync|
000000011011000000010000000000000111000000111000000000000000000000110000000000011100011011011011011011100100100
000000010000000000001000000111111111111111111|HSync|00000000000001100001000001000000011100000011100000000000000
0000110000000000011100011011000000011011000000011100011000010000000000001000000111111111111111000|HSync|0000110
000000110000100100100100001110000001110000000000000001100000000000001000110110110001111110111000000111000110000
10000000000001000000111111111111000000|HSync|000000011011000000000000010000000000111111000010010000000000110110
110110011100100100100000111111011000100100011011010010010000001001001000000000000000000000|HSync|00001001000000
000000000000000001001000000000001011100000000000000000000001101101101101101101101101101101101101101101100000000
0000000000000000000000000000000|HSync|0001110100000000000000000000000101110000000100100000000000000000000000000
11011011011011011011011011011011011011011011000000000000000000000000000000000000000|HSync|000110110110110000000
101000000100100100100010011011011011000101101101000111111111011011010010010010011011011011001001000000000101101
000000000110000000000000|HSync|00011000001000000010110100000001000000010001001100000001001010100010100001101100
0111000000000000010000000000001011011001000101000000101000110110000000000000|HSync|0101100000000100000001010000
000100000001000100110110110101111011011010000000110111110000000000000100000000000010110000010001010000000000000
00110000000000000|HSync|111110110110000010000101000010000000100000010000000010011000000000000000000000111011000
001001010001001000011011001001001000101101101000000000110000000000000|HSync|00011001000000001001010101001001010
000001001000001000001100000000000000000000001111101100001000000000001101101100000000100010100000010100000011000
0000000000|HSync|0001100000100100100101010100101000100100100100100000000110000000000000000000000001110110100110
11011010010011001000000001000101000000101000000110000000000000|HSync|000110110110110010101101101010100010010010
010011011011000000000000000000111111111000000010011011011010010000000001001000000000101101000000110110110000000
000|HSync|01001001001001001001001001001001001001001001001001000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000|HSync|
FTF = FTF(TB)
Additional Hints
(Decrypt)
Oynpx cvkry
Treasures
You'll collect a digital Treasure from one of these collections when you find and log this geocache:
Loading Treasures