RE: [stella] AtariVox EEPROM file format

Subject: RE: [stella] AtariVox EEPROM file format
From: <stella@xxxxxxxxxxxxxxx>
Date: Tue, 30 Nov 2004 08:29:48 -0600
37 character set = 6 bits per character
8.3 format = 11 characters * 6 bits = 66 bits < 9 bytes

OR

Since only 37 out of 64 possible values are represented in those 6 bits, you
can use the 2 most significant bits to signal the end of a filename or the
beginning of the file extension (assuming ext is always 3 characters).

Character set:
    0 = _
 1-26 = A-Z
27=37 = 0-9

010100 000101 010011 010100 100101 11 000101 011000 000101
------ ------ ------ ------ ------ -- ------ ------ ------
  T      E      S      T      9    .    E      X      E

# bits = (# characters) * 6 + 2 = (8) * 6 + 2 = 50 bits < 7 bytes

Or if an agreed-upon lookup table for common characters can be created, a
flavor of Huffman compression can potentially shrink the filenames even
more.  Especially since there's elbow room to play with in those 6 bits.
The downside, naturally, is more code to de/compress filenames, but
someone... perhaps say... Mr. Jentzsch might be able to drum up an
uber-tight de/compressor just for this purpose. :)

Sorry if I rehashed anything or if this is all just kinda "well, duh".  I
very quickly scanned through this thread.

-Lee



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