first saw this thing around 12 years ago on an AS/400 terminal. Our neckbearded Lead Programmer was supposed to have programmed it in RPG but probably this thing is even older?
[ skade sl ] ls -la *
-rw-r--r-- 1 skade staff 331 Jul 22 1998 Makefile
-rw-r--r-- 1 skade staff 417 Jul 22 1998 README
-rw-r--r-- 1 skade staff 689 Jan 18 1994 sl.1
-rw-r--r-- 1 skade staff 7.0K Jul 22 1998 sl.c
-rw-r--r-- 1 skade staff 4.1K Jan 18 1994 sl.h
-rw-r--r-- 1 skade staff 980 Jan 18 1994 sl.txt