Chipper assembler is written by Christian Egeberg.
The only place I was able to find the source was in David Winters zip file of Chip-8 goodies. I suspect it was posted on Usenet based on other locations I have seen the document that accompanies the assembler.
Just copying into my repo for the purposes of preserving it.
gcc CHIPPER.C -o chipper
Assembling a Chip-8 ROM
./chipper output.rom input.asm