This is the source code of XFD's SZDD slave, for the curious.

SZDD is a weak LZSS compressor, which was used by Microsoft for many years
in their installation software - all those files with a letter taken from
the end of their extension, eg HELLO.EX_

Thankfully, one day Johnathan Forbes decided to work for Microsoft, and
happened to sell them his LZX compression technology, which is state of the
art as far as LZH is concern. So now Microsoft use LZX compression in their
installation archives, now under the guise of "CAB" files (I'm working on a
CAB slave for xadmaster).

This SZDD slave has only been tested on a few files, so it may not be
entirely perfect. If you have a file it can't extract, please send it to
me.

Note that this slave does not support 'KWAJ' files, which replaced SZDD as
the secret undocumented piss-poor compression format in the 1996 Microsoft
Setup Toolkit. If you have an actual algorithim for this format (or are a
skilled Windows programmer and could hack it out of MSINSSTF.DLL), please
contact me.

 PERMSSN    UID  GID    PACKED    SIZE  RATIO     CRC       STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                  245     487  50.3% -lh5- 8e1f Jun 29  2000 Makefile
[generic]                  399     488  81.8% -lh5- fb15 Sep 16  2000 szdd
[generic]                 2463    5259  46.8% -lh5- 94c0 Sep 16  2000 SZDD.asm
[generic]                 1255    2582  48.6% -lh5- aec7 Jun 29  2000 SZDD.c
[generic]                 3156    5980  52.8% -lh5- f2fa Jun 29  2000 szddexpand
[generic]                 2660    5991  44.4% -lh5- e243 Jun 29  2000 szddexpand.c
[generic]                 3007    5748  52.3% -lh5- e441 Jun 29  2000 szddinfo
[generic]                  900    1993  45.2% -lh5- 6e95 Jun 26  2000 szddinfo.c
[generic]                  170     269  63.2% -lh5- ae89 Jun 29  2000 testme
[generic]                  685    1196  57.3% -lh5- ac4c Sep 16  2000 xfd_SZDD.readme
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total        10 files   14940   29993  49.8%            Aug 24  2002