I’m no engineer :) but for your date problem can you use the end/maturity date converted to a Julian date and work backwards?

you COULD pgm the Excel sheet to act dynamically exactly like the stack does...

That’s what I’ve done. However, right now, for each function I enter, I have to enter the corresponding Excel formulas. E.g. if the DM42 function is “X>0?” then in Excel I have to type the appropriate “IF(....)” formula and in effect tell the spreadsheet what the stack should do. Which is nice as it forces me to think about what the stack does.

What would really be cool is if I could get the sheet to recognize the DM42 function and automatically insert the corresponding formulas. I don’t think that is possible. And anyway it occurs to me that I’d be basically retreating to the familiar instead of forcing myself to learn the new.

Wow, this thread fascinates me (and makes my head hurt!). I haven't picked up my HP12C in YEARS...I wouldn't even know where to begin without Bloomberg, Intex and Excel!

by "act dynamically" I meant an animation

if you did that I wanna see it!

Oh, that would need VB - I mean the goal is to program the calc, not to get sucked into programming VB/Excel ...

Right? I mean, the sensible thing is to type in the CUSIP and read everything off the screen ... but that’s no fun. And suppose you’re stranded on a desert island and need to evaluate a bond?

Back in the day that's exactly what I used my 42s for as a young engineer - I could take that with me out to the shop floor to troubleshoot and tune equipment / machinery (with programs I had written) on the fly without having to go back to my desk all the time. It was awesome.

I didn’t know enough about the calendars to understand what you meant at first, but I now see that is how HP did date calculations. https://archived.hpcalc.org/hp42s/programs/date/olddate.html?fbclid=IwAR176kIGajlg6ahd7Ar8OGFsOOwE vv8sIRxtaXpKKQE9udQxpyMgu80lpZs

The DM42 has DATE+ and DDAY built in, fortunately.

I’m trying to do something different, basically if I have Oct 16, 2020 and add 4 months I want to get Feb 16, 2021. And I have that working fine. My remaining issue is that if I have Oct 31, 2020 and add 4 months I don’t want Feb 31, 2021, I want Feb 28, 2021 unless 2021 were a leap year in which case I’d want Feb 29, 2021.

I think I found out how to do it. I just use DATE+ to add 0 days to the date, if the date is Feb 31, 2021 the function will return an error, there is a flag 25 that tells the calculator to ignore an operation that results in an error, so that’s sort of a test I can use.

Never was an HP 42CV. There were the 41 series that included the 41C, 41CV and 41CX. Each was an upgrade over the other. THE calculator of choice for Engineers and Surveyors. British Airways and Air France always had a 41 onboard the Concord, and every space shuttle mission ever flown used a 41 as well. I've got a box of 12 or 20 of them in a closet. Along with many of the "modules" that were used with them, including the "Financial" module. More than 20 years ago I came up with a repair to the magnetic card readers that would fit the 41 series; the drive wheels would get gummy with age and not pull the card through. It was a simple fix IF you had the right materials, that cost me less than a dime. So I joined the forum at www.hpmuseum.org and for the cost and time of sending ME a picture postcard from your part of the world, I would send YOU the materials and instructions to fix your card reader. I got postcards from around the world and I've still got the stunning scenic photo book of Blue Sardinia that Luigi sent me.

https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=57

Nowadays, I use an HP41C app on my smartphone. :rolleyes:

Haha, good points! I actually love building things in Excel/VB for fun, but the calc programming is over my head. Super cool that you are doing it, great thread.

Honestly, it is over my head too. I’ve gotten slower and stupider with age, plus I’m so much busier than I was as a teen, trying to do this in 10 minute snatches between paying work and honey-dos and volunteer work. I miss being young, mentally agile, and a whole summer of nothing to do but futz with stuff.

I have a HP41?? somewhere. Going to find it and see if it still works.

Yes, 41 !
The gold standard.

So - does anyone still use a physical calculator in their work? Or is this just a hobby and collector thing now?

Way back in the 80's during my early years at land surveying, the HP41 was the ticket as HP had developed a "Surveying" ROM that in it's module form would plug in to the back of the calculator. Did all kinds of Surveying routines. Even made the one old fellow I knew retire his palm sized Curta mechanical calculator. Now if you want to see a really cool mechanical device, go check one of those out. Highly collectible back then I imagine even more so nowadays.

So anyway, I got pretty good at programming simple routines for the 41 that the ROM wouldn't do, and other times, well......

The crew loaded up in the old suburban one morning and we had about an hour travel time to the job at the new industrial park. We were to meet with an Engineer on what he needed us to layout. The morning joint had already been passed around going down the road and I didn't partake. But I did grab Joe the Party Chief's HP 41 while he was driving.

Now the 41CX had a built in clock. That and more memory set it aside and above the 41 C and CV variants. A clock meant you could (of many things) set an alarm. So I calculated our travel time and what time we would probably meet the engineer on site....and went to work programming.

I'm looking at my watch. It's coming up on 8:30 a.m. and Joe has a really good buzz on. He's got his calc on the hood of the suburban and talking to the Engineer making a few calculations, and while in the middle of making some calcs I see my watch hit 8:30. Bingo. Party time. Joe's HP 41CX starts beeping incessantly and uncontrollably with the text

EAT AT JOES

scrolling across the screen. He's flipping out. I'm hiding behind the suburban about doubled over laughing. It goes on for about 30 seconds and he has her back under control.

30+ years later, Joe is still my friend and we occasionally laugh over that story.:D:D

Just for fun several years ago.



http://forums.pelicanparts.com/uploa...1602662882.JPG

Where is the "CRAY" module?

NVTS 2.4 Module.

Seriously, it was all in fun with a Surveying forum since we all relied on the old 41's for so many years. Enjoy your new calc.

I just ordered the hpmuseum’s full USB stick of goodies!