What is the difference between HEX-80 and Intel HEX format?
Probably negligible, I'd assume the older format is limited to describing 64KB
http://www.keil.com/forum/684/
You're biggest problem with the formats of the era was implementation, and how specific people wrote code to generate and process the output, and the sometimes sloppy or confused way they did it. I guess they didn't have forums in those days, and tried to figure it out for themselves using the documentation and examples available to them.