PDS or Programmer Development Systems is the name of a hardware and software development kit by a company of the same name. Both the software and the hardware including a PC, PCB and custom software work together as one and won’t function without the other. Although, source code still exists that was programmed to be assembled with the PDS. It supports many different base CPUs, such as 6502, Zilog Z-80, etc. Although, this particular document pertains to the 6502 CPU programming.

This document contains enough information to understand many stray pieces of source code and to possibly convert these pieces of source code to another public domain assembler or to design a custom assembler yourself based on PDS.