The contributions, from the Wikipedia entry about him:
"In March 1995, Kildall was posthumously honored by the Software Publishers Association (now the Software and Information Industry Association) for his contributions to the microcomputer industry:[3]
- Introduction of operating systems with preemptive multitasking and windowing capabilities and menu-driven user interfaces.
- Creation of the first diskette track buffering schemes, read-ahead algorithms, file directory caches, and RAM disk emulators.
- Introduction of a binary recompiler in the 1980s.
- The first programming language and first compiler specifically for microprocessors.
- The first microprocessor disk operating system, which eventually sold a quarter of a million copies.
- The first computer interface for video disks to allow automatic nonlinear playback, presaging today's interactive multimedia.
- The file system and data structures for the first consumer CD-ROM.
- The first successful open system architecture by segregating system-specific hardware interfaces in a set of BIOS routines.[22][23][24][25]
"