The never-released HP-72S / HP-74S - the successors of the HP-71B

[J-F Garnier]

(04-01-2021 05:39 PM)Jake Schwartz Wrote:  The amazing thing is that all this stuff could probably have been done...nothing seems ridiculous here. More "future retro" :-)

You've got it !

The 72S/74S never existed of course and, to my knowledge, no such projects ever existed inside HP.

My "Titan X" project (as I'm calling it) is to answer to this question: what would have happened next if the 71B had been a big success for HP?

So let's image:
We are in 1987-1988. The 71B, thanks to a great marketing strategy, is a big success and is even eclipsing the already-old 41CX, so the question is how to extend the 71B market and lifetime.
No revolution intended here, just an evolution, in the same way as the 41CX followed the 41CV, and the 28S is going to replace the 28C.
The major points to address are identified as:
- a bigger screen: it's not possible to continue to live with a 22-character display,
- larger memory: 16KB is definitively not enough, and the 4K modules absolutely obsolete,
- a faster CPU: the HP-71B was initially designed to run at 1MHz, but had to be slowed down to about 640kHz, making the HP-71B a quite slow machine. This is no more acceptable.

Actually, I answered most of these concerns in my Emu71/DOS long ago, my three main motivations of the time were to get a HP-71B with: big memory, high speed and large display.

But my today's Titan X project is different, it is to imagine what a real machine could be. So I used the Emu71 for Windows of my friend Christoph as a basis, and built Emu72, an emulator of the 72S and 74S machines.
You can find this emulator on my new emu72 page:



The HP-72S is fully functional, with its own brand new ROM 3EEEE derived from the HP-71B 2CDCC and providing extended functionalities (see the documentation on my site).
It's so nice to now view the full CAT output, or a complex value without having to scroll the display!

The HP-74S is working too, but still as a prototype using the same HP-72S ROM and so not using the full multiline screen capability.

Experiment, and enjoy !

J-F