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teenix · 12-21-2018, 01:46 AM

Hi all,

Sadly, I have to give up on the HP-81 emulator, which would have completed all the LED calculators of the day.

I have the actual mechanics of it working, but try as I might, it is just too complicated trying to sort out the various functions and math behind them. It is way more than just a printing version of the HP-80. I don't think I could ever guarantee a proper outcome.

Maybe one day...

cheers

Tony

**rprosperi** · 12-21-2018, 01:59 AM

(12-21-2018 01:46 AM)teenix Wrote: Sadly, I have to give up on the HP-81 emulator, which would have completed all the LED calculators of the day.

I have the actual mechanics of it working, but try as I might, it is just too complicated trying to sort out the various functions and math behind them. It is way more than just a printing version of the HP-80. I don't think I could ever guarantee a proper outcome.

Thanks for giving it a good try Tony; I suspect you will not be able to let this go permanently though...

Of course "It is way more than just a printing version of the HP-80" makes me want to go read the manual. A good holiday break To-Do! So, thanks for pointing that out.

Thomas Okken · 12-21-2018, 09:53 AM

(12-21-2018 01:46 AM)teenix Wrote: Sadly, I have to give up on the HP-81 emulator, which would have completed all the LED calculators of the day.

I have the actual mechanics of it working, but try as I might, it is just too complicated trying to sort out the various functions and math behind them. It is way more than just a printing version of the HP-80. I don't think I could ever guarantee a proper outcome.

Not criticizing, but curious: what is the problem? If you can emulate the hardware and you have a ROM image, doesn't the math take care of itself?

teenix · 12-21-2018, 12:25 PM

(12-21-2018 09:53 AM)Thomas Okken Wrote: Not criticizing, but curious: what is the problem? If you can emulate the hardware and you have a ROM image, doesn't the math take care of itself?

The hardware is just a "shell". The display, keyboard, switches and printer are functional but no code behind it all. I don't have the source code, I only have the owners manual to go by. If I had the source code, I'm sure I could figure it all out, but I think getting hold of it is unlikely.

There is a list of equations at the back of the manual, and I have translated and code tested some of them, but not all as I can't work them out. For example, finding the bond yield on page 121 by translating the previous bond price equation to solve for (i), (yuck, unfortunately my math brain is not that good) and I can't even be sure there are no errors in the equations. The manual has plenty of corrections added.

It gets even more complicated with different operating modes, and perhaps not all the required equations are there.

I've spent quite a bit of time on it so far, but I realised it may not be practicable to continue.

cheers

Tony

Harald · (This post was last modified: 12-21-2018 09:25 PM by Harald.)

So is the ROM all you need? Or are you also unsure about how the hardware behaves?
I would have thought if it is just the ROM, we could convince someone to let Bernhard have a go at reading it.

Cheers,
Harald

teenix · 12-21-2018, 11:58 PM

(12-21-2018 09:24 PM)Harald Wrote: So is the ROM all you need? Or are you also unsure about how the hardware behaves?
I would have thought if it is just the ROM, we could convince someone to let Bernhard have a go at reading it.

Cheers,
Harald

It would take a bit, but I'd be confident of getting it going with the code.
I haven't seen inside the unit, so I'm not sure what chips are in there. I think the ROMs in the HP-80 are in a hybrid module.

cheers

Tony