Accessing the old Eaton D500 PLC

I am more of a newcomer to the PLC world with the experience related to Allen Bradley and Siemens software. The D500 is a new animal for me with it's DOS based system. I am needing some guidance on how to access the program since my laptop is running 64 bit and the program is (I think) 16 bit. I guess it's a two part question.
1. What software do I need to run and view/modify this type of PLC?
2. How do I download the software and access the program?

Thanks in advance! I am sure more questions will follow once I get into the program.