Go To in Woodstocks

[teenix]

Hi Bernhard

Thanks for the response.

I'm still not sure if I get it tho...

This is part of key press code that confuses me, I think after pressing '7' key.

01547 load constant 10
01550 c + 1 -> c[x]
01551 if n/c go to 01531 // this seems ok - in same ROM page
01531 p + 1 -> p
01532 if 0 = s 4
01533 then go to 0412 // this seems odd - jumps to ROM 1 from ROM 3
....
00412 c + 1 -> c[x]

There are 2 [go to] instructions without any bank switching but jump to different ROMs in the same 8K bank. I have observed this behaviour when I ran an emulator on the web, but I thought a general [go to] was limited to the 8 bits in the instruction, assuming no delayed select or bank switch previous.

Yes, I got all 6 models working. lots of late nights over many months after my work shift. There were some interesting problems to solve as even the code listings seemed to have errors. I suspect maybe HP put some odd 'bugs' in the patent listings to fool those who might want to take advantage of them :-)

You are right I could not get the HP70 code as it doesn't seem to be available anywhere, so I reasoned it out and wrote what I thought it should be using the simulator/compiler I created. I based it loosely on the HP80 as much of the functionality was the same, but I had to create new code for the other stuff. It won't be exact code from HP but it seems to work correctly as per the documentation that I have available.

If you would like to visit the page, the Classic project is freely available at http://www.teenix.org and you can simulate and experiment with the code for each model.

It also has all the details to build a real calculator. The one circuit can run all 6 models plus I'm sure others as well. The PC software handles the communications with the calculator to change models via the USB port and can upload HP-65 programs to the memory cards.

These cards also work like the real HP-65 but I couldn't design the complicated original setup, so the cards are based on a miniature I2C memory chip. I originally had 1 program per card to try and be more realistic but they would be too expensive so the memory chip holds 64 programs and you can store a whole library like EEpac1 on the one card. They slide in the usual position under the display to be read/written to and can be removed and swapped for others.

cheers

Tony