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Would the HP-15C Limited Edition Firmware Age Away?
03-19-2018, 07:54 PM
Post: #29
RE: Would the HP-15C Limited Edition Firmware Age Away?
Hi Mike,

Tony is completely right that that is how the microcode in the calculator makes it behave.

I did find the HP-65 difficult to use initially but that's my background - I'd been spoilt with later programmables that also show the step number. The HP-65 actually starts by loading in a default program that does the A-E keys. If you power on, switch to W/PRGM and SST through you'll see the program. I thought that was neater than the HP-67 which has an internal flag that you can't see and no obvious default program. The downside is I often key a program into a HP-65 and forget to clear the default program first. You end up with, typically, two "LBL A"s in the program and your program only working every second time (and doing 1/x every other).

Now, if you'd done what you did but pressed 4 divide before switching to WPRGM, you would have been even more confused. I was sure I'd done something seriously wrong the first time I tested that on the HP-65 emulator.

You'll see "81" in the WPRGM display and that isn't in the program. The way the (very early) calculator works is what gets displayed is the current calculator operation; not necessarily the current program step. It is confusing and it's one of the first things they improved with later programmables. (The "81" is because the last operation was a - manual - divide). See the HP-65 Owner's Handbook, bottom of page 62.

Bottom line: sounds like I need to fit the same three lines of code to not update an unchanged display, into the HP-29C emulator, and probably my recent ones too (21, 25).

You should get improved speed if you do the "install" option (tap the display digits to get the menu and help to get to my site. There is an "install" link on the hp-65 page. That should result in everything running locally and it shouldn't matter how good or bad your internet speed is. Some countries / ISPs charge for data. Having it all local also cuts any of those sorts of costs.

Thanks for your help with this.

- Greg from
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RE: Would the HP-15C Limited Edition Firmware Age Away? - Greg - 03-19-2018 07:54 PM

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