An LFSR is a Linear Feedback Shift Register. There are many possible configurations, this page demonstrates the pattern-generating capabilities of a simple structure. The rightmost bit is examined: a 1 will result in a white pixel, and 0 will produce a black pixel. The bits from the two selected taps are XORed together, and the result is fed back into the register at the leftmost end. This shifts the rest of the register to the right by one position. The previous rightmost bit is discarded.
This process is repeated continually, plotting new pixels until the image is filled up.
The shift register length has a big effect on sequence duration - some configurations produce sequences measured in millions before they repeat, others can repeat after a few hundred.
Changing the wrap width will make a 'carriage return' after the specified number of pixels and present the same sequence differently, revealing new textures.
Have fun divining the mysteries of the future within the patterns!
Some historical tap/length configurations of interest for digital noise generation:
0 1 14: Texas Instruments SN76489, used in the BBC Micro
0 3 16: General Instrument AY-3-8910, Sinclair Spectrum 128K and many other systems
1 6 23: MOS SID, Commodore 64 noise
0 18 31: Roland TR-909 noise source
