VCR Controller Code
A while ago, Curt Welch, Andy Kinsman, and I determined most of the algorithm
used by the VCRPlus controller, and published an academic paper on this.
Click for the
text of the paper, Figure 1, Figure 2, or in pdf.
(Note that there's a typo in figure 1, where the input to box 6 should be
c5c4c3c2c1c0. There's also a typo in example 2, where top 28 should
be top 66.) Some history is on Curt Welch's
The citation for the paper is:
K. Shirriff, C. Welch, A. Kinsman, Decoding a VCR Controller Code,
Cryptologia, 16(3), July 1992, pp 227-234.
We haven't done any more research on the 7 and 8 digit codes, nor are we
aware of anyone else who has. The algorithm we published can be considerably
simplified, and I have some incomprehensible
rough notes on how to do this and where the key comes
Copyright 2000 Ken Shirriff