9101A manual

[bshoring]

Thanks, Tony, for including the U.S. Patent info for the HP-80 in the documentation for that simulator. This is of particular interest to me as I recently acquired an original HP-80. After getting it, I worked through every problem in the manual. While I have had an iPhone emulator for RPN-80 for about 5 years, it wasn't until I got the physical machine in my hands that I really worked though all the financial problems it solves.

If we put ourselves in an early 1970's mindset, the HP-80 is actually a computer, and a pretty sophisticated one at that. From the patent info plus the "For the Inquisitive" view of your simulator, it is apparent to me that the HP-80 has exactly the same memory capacity (for storing data) as the HP-35, with just the stack, plus the M register and the A&B scratch registers. Yet it has root finding capability plus all the financial capability of later machines. Even the cheaper HP-70 has much more storage capacity with a separate register for n, I, PMT, PV & FV, but the 80 has to do it all in the stack. I am just blown away with how the engineers, with less than a year, managed to build so much into a machine with such limited capacity.