1989 marked the "The Sixth International Obfuscated C Code Contest" Copyright (c) 1989, Landon Curt Noll & Larry Bassel. All Rights Reserved. Permission for personal, educational or non-profit use is granted provided this this copyright and notice are included in its entirety and remains unaltered. All other uses must receive prior permission in writing from both Landon Curt Noll and Larry Bassel. Instructions for use: Run make to compile entries (it is possible that on System V or non-unix systems the makefile needs to be changed). Look at the source and try to figure out what the programs do, and run them with various inputs. If you want to, look at the hints files for (minor) spoilers. This year, the Grand Prize was given to the most useful program. The "Strangest abuse of the rules" award was given this year to stress the fact that starting in 1990, compiling entries must result an executable regular file. In two other cases, we included System V portable versions of winning programs. The makefile always uses the portable version of the "Best self modifying program" because there as no loss of functionality in using it. In the case of the "Best game" winner, however, some functionality is lost in the portable version and so the makefile uses the original program. System V users may need to change the makefile to use the s5 version. See the hint files or the Makefile for details. Rules and results were posted to comp.lang.c, comp.sources.unix, and alt.sources. They have been made available on a wide number of Usenet archive sites such as uunet. The 1989 winners will be published in the Micro/Systems Journal.