Technical notes
---------------
As the source is packaged in a Tar file, it is missing information about
filetypes that is crucial to RISC OS users. I suggest that RISC OS users
obtain the binary distribution in Spark format and merge in the sources
contained here.

RISC OS is a 32-bit system, using Acorn's ARM processor. The ARM does not
have opcodes to perform 16-bit memory accesses, being a very pure 32-bit
RISC chip, so much of the source uses the 32-bit int type rather than the
16-bit zword_t type. This is a significant performance boost under RISC OS,
but would probably be a performance hit on any other machine.

Also, the ARM is little-endian, and incapable of unaligned memory accesses.

Zip 2000 uses a lot of operating system calls. Hopefully the names of
these calls should explain a lot of them, but much may remain obscure to
non-RISC OS programmers. Web searches may throw up some RISC OS programming
information, and the Usenet newsgroup comp.sys.acorn.programmer may be
helpful.

Sound playback is courtesy of a RISC OS module called DataVox - Zip 2000
simply converts sound to 8-bit logarithmic mono and passes it to DataVox to
play. The next version may use a more modern playback module capable of
16-bit stereo sound. Music playback is courtesy of a RISC OS module called
QTM.

The interpreter core interpret.c here is not used in Zip 2000 - the
assembler version interpret.s is used instead. However, interpret.c is kept
in sync with the assembler version for my own sanity, and should be
fully functional.

There is much in Zip 2000's coding that I am not proud of. In particular
there is too much interlinking between source files, initialisation is
hairy, and much that should have been subroutined wasn't. Some
simplification should be possible soon when definitive Blorb versions of
the Infocom games are available and it is possible to remove support for
the old Infocom graphics files.