> Good, so it's not a format clash in Jmol, but merely an extension clash in
> general... nothing we can do about... (whoever came up with the idea that
> a
> file must be 8.3 ???? :)

I think that the 3 character extension came about because one can store 3
upper case characters in 2 bytes. If you restrict your character set to 40
characters (26 upper-case chars + 10 digits + _ + 3 more) then 40*40*40 =
64000 ... 64000 < 65536 so it will fit in 2 bytes.

This trick was also useful for symbol tables in early for FORTRAN
compilers, where 6 chars could fit into 4 bytes.

(Separately, you could also fit a 6 char FORTRAN symbol into a single word
on a 36 bit machine which used a 6-bit character set ... machines from
General Electric, DEC PDP-6, DEC PDP-10)

I may be mistaken, but I think that the file systems for the DEC PDP-11
(like RT-11) used 6.3 file names ... 6 bytes in total.

Not sure where the '8' came from in '8.3'.

CP/M had 8.3 file names, so MS-DOS inherited 8.3 directly from there. But
the use of 8.3 may well have predated CP/M.


Miguel



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