33s, 35s or 15cLE--which to buy?


Hello all. I'd like to add at least one of these to my collection for not only my library but also as a function set and programming enhancement to complement my already existing predecessors.

Here's what I've got in comparison:

An original lineage 15C
an HP-42S
and an HP-32S-II

So, with these as a base, which model or models should be my next investment?

Thanks in advance for your help


I have all the models you mentioned.

The 33s is basically an enhancement of the 32SII with the main advantage of a two-line display. If you like the 32SII, then you will like the 33s, which is also the least expensive programmable RPN calculator currently made by HP.

The 35s is a step backwards, and not worth owning IMO. I don't use mine.

The 15c LE is an overpriced disappointment, with faster speed offset by short battery life and annoying bugs. Mine also suffer from random keyboard repeating errors.

My 2¢


Due to the poor quality and performance of the last two models I'd say that the purchase of an HP scientific calculator is no longer an investment.


Between these three calculators, the HP33s provides a full-featured scientific RPN calculator with a very nice price point. A little ebay prowling can net one for around $20.

I have a 15C that I still use, but I'm not sure I would go with one of the 'new' 15Cs. On the other hand, if I could get the 'same' calculator (who needs speed, give me the batteries that last FOREVER) for under $50 I would consider it a winner.

We bought a 35s for my daughter to use on her FE exam. I've used it a few times, and it seems OK - but I think the discussions here have highlighted some serious flaws in the unit. Unfortunately, although it sounds like the shortcomings are fixable, it doesn't seem like HP will be updating that model.

What I find tempting now is the HP20b reprogramming project. It sounds like a fantastic unit with the sole drawback of stickers and labels on the keyboard.


What I find tempting now is the HP20b reprogramming project. It sounds like a fantastic unit with the sole drawback of stickers and labels on the keyboard.

So far Eric's overlays are durable and cheap enough to have a couple of spares on hand.


Given what you already have, it' just a matter to choose the disappointment flavor you prefer. 33S, 35S, 15L... each has its own way to disappoint.

I think that the 33S is the less-buggy from this trio, but the display just evolved from "absolutely unreadable" to "barely readable", and the colors of the keyboard legends will heavily stress your eyes (leaving the angled legends alone).

The 35S has a lot of bugs, its display is also very uncomfortable to use. The keyboard legends are better than in the previous case.

The 15L comes from the internal HP development team, which makes a very positive difference from the other two; and recreates the classic vintage model. Ergonomics are good (not as good as the original, but close), and if eventually HP releases new firmware, the bugs may go away (the 15L may be updated, while the other two models cannot). Apart from the bugs, the numeric-only display may look as a limitation nowadays.

A 30B, converted to a WP-34S will be the best suggestion, IMHO.


Definitely go for a WP 34S :-)

- Pauli



I do not have a 33S, so I cannot commnt on it, though I do not like the looks of it much.

The WP-34S is a great integration, but I would not recommend it for sustained day to day use because you will need stickers on the keys and they will peel off quickly (especially if you use the very tight HP-30B case).

The 15C LE is a nice classic, but the PSE bug is annoying and the numeric only display is a limitation if you program because the program steps are shown in code (the line-column coordinates of the keys). It is also quite pricey.

Among the 3 models you are thinking about, I would recommend the 35S despite the bugs (which I did not notice really) and some oddities like the shifted STO key and the hard to read display annunciators. But the format is nice, a bit like the HP-65/67 classics, thinner and lighter (and LCD). Programming is easy (old style, not RPL) and the alphanumeric display makes it easy to read your programs. Memory is large (32k I think). Some common conversions are directly on the keyboard, which is handy if you use those a lot. At ~ 50$, it is a very good deal.

Decisions, decisions... or buy them all!


Pardon my misunderstanding but, what is a WP-34S?


The WP 34S is a repurposing of HP's 20b and 30b business calculators for scientific purposes. It operates like the 32sii but with all the integer functions of the 16c (and even a few extra) and most of the functions of the 42s plus a whole swag of extra functions and capabilities.

Check out the development site. There is a comprehensive manual in the distribution which should give you an idea of the device's capabilities.

As for the actual repurposing, overlays and programming cables are available as are preprogrammed devices.

- Pauli


Well, thanks for all your advice. Amazingly, on eBay (of course), I found a 33s. This seller offered returns (just in case I'd need it) and he had several BRAN' SPANKIN' NEW ones in stock so, I bought two. YIPPEE!!

The topper was that earlier today, I was computing some integrals on my 32S II. They were taking unusually long calculation times on SCI 4 and FIX 4 settings. Yes, I know I could've stepped down to SCI 2 or FIX 2 but, it shouldn't be 15+ minutes on 4, should it? I figure this 33s should be much faster than my 32S II and that's why I picked the 33 over the 35. Is the 33 faster? If so, any benchmark figures?

As for the looks of it, considering it's an upgrade from my 32S II, the newfangled curved keys, although not my first pick for a facelift, are small adjustments to pay for getting a jump up from my old standby.

Edited: 25 Feb 2012, 10:07 p.m.


If an integral takes 15 minutes on the HP-32SII you can expect at least 6 minutes and 30 seconds on the HP 33s (and perhaps no more than 90 seconds on the HP-15 LE). It was a good idea to buy two. I am on my third one (one broken key on each of the previous two -- they still register, but look unpleasantly loose).


The WP-34S is a great integration, but I would not recommend it for sustained day to day use because you will need stickers on the keys and they will peel off quickly (especially if you use the very tight HP-30B case).

Hm... I don't know about your experience, but I've been using a WP34s as my daily calc now for many months. If by "peel off" you mean that the sticker will lift from the key, I can say that I *never* had any problem of that kind.

If you mean that the ink will peel from the vinyl substrate, that happened with the old, non-coated overlays; the more recent ones have a thin lacquer coating that improves overall durability, improves contrast, and prevents peeling - I had no peeling at all with the coated one.

This is my personal experience, YMMV! :)



My experience with the overlays is the same. No problems and no sign of ware or peeling so far.

- Pauli


I totally agree. Although the process of applying the key stickers and overlay is not particularly fast, it isn't nearly as difficult as I expected (and I'm clumsy). I've done it twice, without problems. The WP 34S has become my main calculator and I've had no problems with anything peeling away.

I really do recommend this machine to any of you who are still thinking about whether to bother. There has quite simply been nothing else like it - ever. I can imagine exploring it for years!

Nigel (UK)


I have both the 33S and 35S. My recommendation is the 33S, provided that you can stand the highly controversial chevron keyboard. Apart from the bugs in 35S, I think that the 33S has a better key press feel than the 35S. After using for several months, I've accustomed to the 33S' keyboard layout and for me, that strange chevron keyboard isn't so strange after all. The 35S is constantly reported to have unregistered key press problem, and I also have experienced that, though I'm not sure whether it is software or hardware based.

Mind you, the earlier version of 33S has the problem of small dot/decimal "." which is difficult to read, but seemed to have rectified in later productions.
The 15cLE is an out-dated technology IMO. I hate programming the 15cLE as it is nearly impossible to debug.


I hate programming the 15cLE as it is nearly impossible to debug.

Unless you know the key-coordinates by heart, which an experienced 15C user does.


The 33S looks terrible and the 35S has serious shortcommings wrt to speed and ergonomics. The 15C LE however is a good choice for someone who already owns a 15C. It's small, it's ergonomical, it's fast, the key-touch is not the same as the original but it is far better than the 35S. Yes, it has a few bugs but I can live with them in daily use. Frankly I don't understand people nagging about this machine, especially in view of the numerous requests in the past to reissue it. Keyboard-issues were a potential problem but that seems to have been fixed (and if not you have a warranty). I would go for the 15C LE. It also looks superb.

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