ITT the ABC Programming Language

#include <stdio.h>

int main(int argc,char argv*[]){
  int i = 0;
  int BUFFA;

  while(argv[i]!='\0'){
    if(argv[i]='a')
      BUFFA++;
    else if(argv[i]='b')
      BUFFA--;
    else if(argv[i]='c')
      printf("%i\n",BUFFA);
    else printf("%s","Error.\n");
  }
}

The difference there is that it's only in the public domain in the US, not anywhere else. You still can't just release your own software into the public domain.
it's also public domain in any country with sensible copyright laws (where any work without a copyright notice is in the public domain).

Also ``recent vintage''.
kids these days... 1987 really isn't that old.