BenSlivka/OS2_PSCHAR
[3.7 KLOC C/ASM, 1.2 KLOC comments] 1988: A character-mode full-screen/visual Process Status tool for OS/2 v1.1. See especially FMT.ASM [555 LOC], which is a compatible and nearly-complete re-implementation of the C run-time sprintf() function in blazing fast 16-bit x86 assembly code.
C