diskOscope hardware

Some synchronous nibble captures

Submitted by S.Elliott on August 29, 2024 - 1:25pm

This blogpost is a quick data dump of raw Disk II data, captured synchronously at intervals of exactly 8 CPU cycles.

Picture 1: Synchronous capture of 10-bit sync nibbles and 8-bit address-mark nibbles

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diskOscope hardware

Nibble Histogram: the seeds of a disk-o-scope

Submitted by S.Elliott on November 28, 2022 - 9:40pm

What is the distribution of raw nibble values of the bitstream a Disk ][ controller would read from an ordinary DOS diskette?

What values would arise from a copy-protected game disk?  Or from a .DSK emulation of a diskette?

This little routine captures incoming nibbles and computes a moving-window histogram of their distribution.  The data usually stablizes after about 8 calls because it applies a base-2 logarithmic decay to the values after each iteration.

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diskOscope hardware
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