>6522 VIA shift register<p>>Unfortunately, I was unable to get it to work.<p>Author blamed this on:<p>>I did not work out how to get the shift clock running continuously and smoothly. Even with attempts at precise timing for shift register reloading... reloading the shift register incurs a delay before shifting resumes.<p>This was in fact a hardware bug <a href="http://forum.6502.org/viewtopic.php?t=342#p2310" rel="nofollow">http://forum.6502.org/viewtopic.php?t=342#p2310</a> , rather famously the reason for C64 having cripplingly slow (300 byte/s !!) Floppy drive communication implemented thru bitbanging in software despite using fixed 6526 CIA. Previous VIC-20 used 6522 and floppy drives had to stay compatible <a href="https://en.wikipedia.org/wiki/Fast_loader" rel="nofollow">https://en.wikipedia.org/wiki/Fast_loader</a><p>Dropping this compatibility and using 6526 CIA hardware shift register results in C128+1571 combo reaching ~5KB/s
The article links to a demo on the BBC micro which is simply mindblowing - <a href="https://youtu.be/oK2D1EdFXMM" rel="nofollow">https://youtu.be/oK2D1EdFXMM</a>
>"This is similar to the description of how the Dungeon Master fuzzy bits are written.<p><i>As can be seen in the screenshot, the 0x88 data bytes soon start reading back incorrect and non-deterministically. But the variance isn't 100% random like weak bits -- the variance is whether the 0x8 bit is late enough to have a chance of being missed. If missed, you can still eyeball that there are patterns and themes to the madness.</i><p>You know, Dungeon Master and copy protection aside, my intuitive mind says there is some form of as-of-yet unobserved/not understood -- similarity between the concept of "fuzzy bits" on old school floppy disks, and that of Qubits, from relatively new school Quantum Physics...<p>Perhaps qubits could be constructed in the same way fuzzy bits are -- use a device which writes multiple pieces of data at a higher resolution -- then measure that data with a device that reads at a lower resolution.<p>Applied to qubits then, whatever the particle size, whatever the region of space that the qubit occupies -- attempt to "write" one by writing multiple points in that same space with a device that can modify smaller points within that space (if the qubit is a particle, then this would be sub-particles), and then read it with a device that reads the entire space (which should read probabilistically now, because it lacks the resolution of those smaller particles necessary for a true, repeatable reading...)<p>I could be completely wrong about this, of course.<p>But intutitively, I sense something there...<p>>"The above results are actually the application of fuzzy bit principles to FM encoded data. In FM encoding, every data bit is interleaved with a clock bit. This results in the bleeding of clock bits in to the data stream on occasion (see the 0xFF bytes in the first run above -- they are likely clock bits). The Dungeon Master protection uses fuzzy bits in conjunction with MFM. This leads to a calmer situation where the fuzzy bit drifts between two valid data bit encodings and does not mess up the clock!"<p>I wonder what could be learned in physics if we tried similar techniques with small particles/small regions of space/small regions of space on substrates...<p>Anyway, physics aside, a truly fascinating article!