PDP8 key (Was: Text encoding Babel.

Fred Cisin cisin at xenosoft.com
Fri Nov 30 23:15:39 CST 2018

On Fri, 30 Nov 2018, Jon Elson via cctalk wrote:
> Those are the 8 possible DEPTHS of the grooves cut into the key.
> So, that gives a possible combinations of 8 to the 7th power, I think.
> These depths correspond (with an offset) to the lengths of the tumblers 
> (pins) in the lock.
> So, if you know what the length of a tumbler is, you can add the offset and 
> figure out what depth groove to cut in the key.

No, they are the depths of the grooves cut into the key.
The low numbers are a shallow cut.
Sometimes, people mistake the #1 cut for not being cut.

Although the combinations are 8^7, often a cut that is one off will still 
work, so there are fewer usable combinations.
And in a conventional lock (non-tubular), it is a BAD idea to have the 
deepest cut right near the bow (handle), or the key will break/wear out 
prematurely.  And some lock companies advise against having an extreme 
difference between adjacent cuts. 1,9,1,9,1 will be hard to get in and out 
of the lock.  And, some lock companies pick patterns of only having even 
number cuts for some positions and only odd numbers for some others.

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