I live in Hong Kong and want to use my VCR G-code programming function
but I do not have access to the G-code listings for the programs I
want to record. I want to record shows from local cable chanels and
also from 3 different satellite dishes. I would like to be able to
make my own Excel spreadsheet where I could generate G-codes myself
for specific shows by imputing the date, time, chanel and length of
recording. What I need is the formula(s) used to compile G-Codes.

I am not a computer genius so I need a concise explanation of how the
codes are generated in order for me to make practical use of your
answer. A satisfactory answer will allow me to code an excel
spreadsheet so I need simple and concise formula(s).

check_six6-ga:

The actual algorithm for computing G-Codes (related to the VCR Plus
codes in North America, and the ShowView codes in parts of Europe) is
a closely guarded secret of Gemstar Corp. There have been steady
attempts over the past thirteen years by several people to reverse
engineer this algorithm, but so far the only reliable processes are
limited to codes of six digits or less. You can find a good summary
here:

http://www.zelczak.com/vcrplus.htm

The Sherriff/Welch work cited was published in 1993:

http://www.tinaja.com/third/vcrplus.pdf

Generally, the complexity of the encoding algorithm (involving
multiple steps/iterations and resulting in potentially hundreds of
millions of outcomes) makes this a difficult problem to solve
(especially as G-Codes will again have differences from the method
described on the first link above). With the information on the two
links here, you *may* be able to make some headway on this problem.
However, given your criteria that a satisfactory answer be one that
will allow you to code an Excel spreadsheet with simple, concise
formulae, it will be extremely difficult to satisfy you. I hope this
comment helps, though.

Regards,

aht-ga
Google Answers Researcher