Customer Reviews

HP 35s Scientific Calculator

5 star:		(123)
4 star:		(92)
3 star:		(34)
2 star:		(7)
1 star:		(14)

 

 

I am a diehard RPN and HP calculator fan. I bought this calculator for the PE exam. HP calculators I've owned include HP41c, HP42s, HP12c, HP17BII, HP19BII, and HP33s. The HP35s is basically an HP33s with most the ergonomic design flaws and quality issues of the HP33s fixed, along with a few added enhancements. It's what the HP33s should have been in the first place. But, along the way, it also introduces a few design flaws of its own.

Obvious pluses: The keys on the HP35s feel almost like the ultra high quality keys on the HP41c, not entirely there because the ones on the HP35s are flatter and have less travel distance, but very close. However, unlike those on the HP41c, some of the secondary colors on the keys are only painted on. How long would the paints last? It comes with a super nice semi-rigid vinyl case. The LCD display is fragile, but it seems to be dust-proof and has excellent contrast. The built-in metric/imperial conversions and constants library are also nice. One major enhancement over the HP33s is the ability for a program to refer to a line number instead of a label name during conditional branching. This feature allows the writing of programs that don't use up a lot of the precious program labels. The equation solver is quite powerful. It comes with built-in equations for solving 2x2 or 3x3 simultaneous equations.

Obvious minuses:

One major annoyance to me is that the HP35s does not have scrolling comma separators as I enter a long number. So, if I enter 12000000, I have to hit the ENTER button to see it displayed as 12,000,000. The lack of real-time, scrolling 1,000 separators makes it very easy to make data entry mistakes. The HP41c, HP42s, or even the lowly HP33s have scrolling commas.

There are only 26 single alphabet program labels and only 26 variables, severely limiting the number of programs one can store, considering the somewhat large 30kB memory available(the HP42s only has 8kB). The manual has a good number of useful programs, but in reality one can store only a few of these programs on the calculator at a time due to the 26 program label limit. I can store more programs on the HP42s even though it only has 8kB of memory. In actual use, most of the 30kB on the HP35s will go untapped.

It's a shame HP chose not to include multi-letter alpha-numeric capability as they did on the HP41c and HP42s. Instead of labeling a program that calculates the time value of money using a single letter such as "T", I'd much rather be calling the program "TVM" or "MONEY" or something easy to remember. The same one-letter restriction applies also to variable names. The listed battery life is on the short side. Two hours of use per day will last the batteries only about 9 months.

Whereas the HP42s offers four types of curve-fitting and has capability to choose one with the best fit, the HP35s offers only linear regression. Also, unlike the HP42s, the HP35s doesn't have any built-in matrix capability to evaluate determinants, inverses, although it does have built-in 2x2 or 3x3 simultaneous equation solving ability as mentioned earlier. You can program all these missing capabilities in but you'll use up many of the precious 26 program labels in a hurry.

The STO key which I use very often is now subordinated, requiring a shift key, whereas the "Mode" key which I seldom use is primary.

The display has much more glare than other HP models I've owned.

Although I will almost never use the algebraic mode except when writing equations, I must mention that its implementation on the HP35s is clumsy. On other algebraic calculators I grew up with, the number precedes a function key (such as COS, 1/x, log) and the function is executed as soon as the function key is pressed. In other words, even though they are algebraic calculators, their function keys work in postfix or RPN mode.

The key sequence is

45

COS

The value of 0.707 is displayed as soon as the COS key is pressed. It's very simple and intuitive. This is also how the functions work on the HP33s. But, surprise, this ain't how it works on the HP35s!

On the HP35s, you have to start by first pressing the function key and then punch in the number and then press the Enter key to get the value.

The key sequence is

COS

45

ENTER

The ENTER key works as the equal sign key in algebraic mode on the HP35s. Hitting the ENTER key now becomes mandatory to get an answer from just about any operation. Although this peculiar algebraic approach may make sense when writing equations, it's highly cumbersome when doing calculations on the fly, especially for someone used to the keystroke efficiency of RPN.

I sometimes scratch my head trying to figure out why for the last 10-15 years HP kept churning out mediocre calculators, with each new one worse than the previous one. Why mess with winning designs and dumb them down to the level of TIs and Casios? Yes, the money is where the masses are and the masses are the high school and college crowd and they use predominantly TIs and Casios. Then it dawned on me that the sales execs, designers, programmers, engineers also have to somehow justify their existence by rolling out new models and discontinuing older but superior models. The HP35s seems to be a step to halt the march toward mediocrity. Does it succeed? Yes, mostly. Although the build quality is good, it certainly could have been designed better.

Even though the STO key is now subordinated, the HP35s fills the need for basic everyday number crunching due to its ergonomic form factor and ease of use combined with a reasonably rich set of functions. The HP50g fills the need for heavyduty scientific/engineering use but is too clumsy for everyday basic number crunching.

I'm sure as I use this calculator more, I will see more of both the pluses and minuses. And, if I were to rate this calculator in comparison with any Casio or any TI, I would give it 10 stars if I could. But I rate it in relation to what I expect an HP calculator should be and so I rate it 4 stars. If the HP35s came with more program labels and variables than just 26 of each (A to Z), multi-letter alpha-numeric data entry capability, matrix capability up to [5x5], 4 types of curve fits and best of fit, primary STO and RCL keys, I would rate it 5 stars.

This is a very nice high-quality scientific calculator from HP. The overall design and capabilities are similar to the HP 32SII (equation solver, unit conversions, etc.), but with several enhancements.

Like many recent HP models, this calculator can work in either RPN or algebraic mode, but I use only RPN. The keyboard layout has been well thought out, with most functions being quickly available directly from the keyboard and a few lesser-used functions available through menus. The keyboard has a traditional HP layout and colors, and the keys have a nice positive feel. A very thorough and well-written printed manual is included.

A new feature with this model is that each level in the four-level stack may hold a real number, complex number, or 2- or 3-element vector. Complex numbers may be entered very simply using the "i" key (or "theta" key for polar form); vectors are entered using square brackets. This design makes it very easy to manipulate complex numbers and vectors.

The calculator includes 30 kB of memory, which is enough for over 20,000 program steps. There are 26 main memory registers (A-Z), six statistical registers, and 800 more memory registers available through indirect addressing. Another new feature of this model is TWO indirect registers, (I) and (J).

A few cons: With previous HP calculators, there was a shortcut for entering exact powers of 10: for example, 10,000 could be entered as "E 4". For some reason HP has dropped that feature on the 35S, so you now have to enter "1 E 4". Not a major drawback, but kind of annoying since I used that shortcut a lot on previous models. Another nit is that the function to convert HMS to decimal hours is labeled HMS-> instead of ->H, which I haven't gotten used to yet.

Overall, the HP 35S is a very well-designed calculator, and I would not hesitate to recommend it as the best general-purpose scientific calculator available today. In fact, I bought three (for home, work, and school).

The 35s is the most interesting calculator HP's produced in a while. While I'm sure their intended market is the legions of dedicated HP users, even if you're not a lover of antiques you should give it a look.

A definite improvement on the 32sII, and in general I would recommend it over purchasing an overly-expensive used HP. While the hardware isn't quite as nice the 35s should have a much longer battery life, and has more than enough memory to hold any reasonable number of programs.

It's physically larger than a 32s and it's not really "pocket-size". Yet it's not that big compared to modern scientifics and the larger display is worth it.

It feels very solid, except for a battery door which pops off a bit too easily. Lithium coin batteries are so much easier to deal with than watch batteries that I'll happily accept the tradeoff.

The keyboard is slightly soft compared to older HPs but that's been easy to get used to. It has a definite click, good-sized keys with a large Enter key, and should seem quite familiar to HP users. Unfortunately it uses painted-on key symbols which I suspect will show wear rather quickly.

Crisp display, easily readable from practically any angle. A huge improvement over the LCDs in HP's older models.

It has RPN and algebraic modes, as well as an EQN key which allows algebraic entry while in RPN mode. Most keyboard functions have an EQN/ALG counterpart, and while algebraic formulas can be used in programs you'll still need to use RPN for conditionals and loops.

The excellent mixed-base number support is a pleasant surprise. In algebraic mode you can easily enter a calculation in mixed bases without changing the current base. (This mostly works in RPN, but there's no way to enter hex A-F without switching modes.)

Programming is similar to the 32s and much of the manual is identical--the only major change is additional memory. The 35s' overloaded keys and simple design make programming much easier than an RPL-based calculator like the 49g+.

Why did it only get 4 stars? Two issues:

No I/O. Being able to backup memory would make me a little happier and I've come to expect this from a modern programmable.

And, RPN programs generally run only about as fast as on the 32s, making its programmability less useful than otherwise. After 15 years I expected to see at least a factor of five speed increase.

In short: I like it, and I think you will too. In terms of price and ease of use it can't compete with, say, the Sharp EL series. (The new HP 10s is a real contender there.) But the HP 35s' programming capabilities set it apart from any of the inexpensive scientifics. If you'll take the time to learn RPN, you'll find writing programs is easier and more convenient than writing the same thing in a BASIC-like programming language.

Tim C is as confused as Charles and is unable to spell my name even though it is printed in the review. I am holding an original HP-45 in my hand. If you type 2 Enter 3 Enter + you get the incorrect answer 6. Tim C's claim of an "error" in HP's implementation starting at the HP-32SII is completely false. I own an HP-32SII also. It works exactly the same way as the HP-45 which predates the HP-32SII by 18 years. I know what I am talking about. I own and use the HP-45, 55, 67, 29C, 41CV, 41CX, 48GX, 49G, 50G, 32SII, 42S, 28S, 50G, and 35s. I guess I need to repeat myself: ALL EARLY HP RPN CALCULATORS REQUIRE THAT YOU PRESS 'ENTER' ONLY ONCE. THE HP-35s FOLLOWS IN THIS TRADITION! Tim C should learn the history before he comments on it. Tim C should buy and use the product before he writes a review. The reviews by Charles and Tim C are misleading. Reviewer Charles has limited experience with RPN and has not explained it correctly. In general you should only have to press Enter once during a calculation with 2 numbers. This is true of the 48G also. Some calculators have a command line at the bottom that is separate from the x,y,z,t stack. For those you MAY press Enter twice but you don't have to. 2 Enter 3 + will work fine. On all the older RPN calculators you enter numbers directly into x and you should not press Enter twice. Again: 2 Enter 3 + will work fine.

I bought the original HP-35 back in 1973, when it cost $395. The "new" HP-35s is better in many ways, but it still misses as a direct replacement for that classic calculator. One of the design goals of the original was that it had to fit in a shirt pocket, and it did. Oddly, the new version is larger than the original, but it does weigh less. HP made the new keyboard larger with larger keys, but IMO the old HP-35 keyboard was easier to use because it was more legible and less crowded. The HP-35s is programmable, but it has no way to store or transfer large user-created programs off of the calculator. That is the main reason I didn't rate it higher than three stars.

I'm glad to see HP making RPN the primary entry mode again. Maybe they'll follow this model with a "new" version of the HP-45 and add a USB port for data and program transfers.

Post Script 2-18-08
I've now had the calculator for a couple of months and find its annoyances outweigh the advantages. The keyboard's poor legibility and odd layout frustrate me every time I use it, and simple functions like clearing a register or a syntax error require multiple keystrokes -- arrrggg! My trusty and worn HP15C is back out of the drawer. Adios HP35s.

I have been using HP's low to mid priced calculators since I bought an HP21 back in 1977. HP lost its vision in recent years with their calculators, abandoning RPN in their lower priced models and producing disasters like the HP6s and the HP33s. The HP35s is a definite sign of improvement. In spite of the gripes I list below, I consider this a good calculator I look forward to the HP35sII.

What they got right:

Good physical design, with good key lettering and key action. Not like their recent designs that are about style instead of clarity and ease of use. Similar to some of HP's older (and better) calculators. The key action is still not quite up to my favorite, the HP32s.

Errors:

The values for COS and TAN calculations near 90 degrees are incorrect in the last few digits.

Deficiencies:

The exponents of displayed values are off screen when the DISPLAY mode is set to ALL or using "ENG ->" or "<- ENG".

You must use 3 keystrokes to enter "h", "b" or "o" after non-decimal number entry. You should NEVER need to do this to any number being entered in the base of the selected mode. I can see were it would be handy for entering nummbers in an alternate base, but only then.

Keys for hex digits A through F are unlabeled in RPN mode and require two keystrokes in algebraic mode - bad design.

The thousands separators do not appear during digit entry; only after ENTER or an operation do they appear. This worked on older HP calculators.

I've been using HP calculators for almost 20 years and am very happy with this one.

The keyboard layout and feel are both absolutely perfect in my opinion. It retains the HP tactile click without having stiff keys with long travel, which is my only problem with the new HP50g (otherwise awesome calculator). I have a big, nasty equation that I used to test my speed with my calculators. It took 30 sec. on my 33s, 25 sec. on my 50g, and 22 sec. on my 48G which I've been using for 10 years. The very first time I cranked it through my 35s, literally <2 minutes after inserting the batteries, it only took 23 sec. This calculator is optimized for cranking through big hairy equations. To me, that's what an engineering calculator is for! I have Mathcad, C++, Matlab, and Mathematica for all the stuff that graphing calculators do, but that's another story...

Pure RPN does take a little getting used to if one is used to the graphing models' RPL, but the 35s implementation is correct. My previous calculator was a 48G, so I found the 4 level stack to be slightly irritating. Took an hour or two to completely get over that when I bought my 33s a while back.

I actually like the tiny batteries instead of AAA because this cuts down the weight of the calculator. AAA batteries in the 35s, which is a very elegant little calculator, would've been insane. Also, what's the alternative? Feeding AAA batteries, 3 or 4 at a time, to a graphing calculator once a month?

Unless it dies on me, I think I'll be very happy with this calculator for a long time.

HP 35s



Programmers & software/firmware engineers beware! If you do any base conversions and arithmetic please read this before considering this otherwise worthy calculator. In *all* previous HP calculators to do say hex addition (Ex: 12F + E9A) you'd simply do this:

1. Select hex mode: SHIFT BASE HEX

2. Enter the first number: 1 2 F ENTER

3. Enter the second number: E 9 A

4. Press + (total 11 keystrokes)



Not so with the 35s! Here's the drill straight from the example on page 11-5 of the manual

1. Select hex mode: SHIFT BASE HEX (so far so good...)

2. Enter the first number: 1 2 1/x SHIFT BASE 6 ENTER

Explanation: Although there's a key labeled "F" you don't use that one when entering hex numbers - you use the 1/x key to enter F!!! After you key in the hex number you still have to tell the calculator you've entered a hex number (even though you're in HEX mode (WHY??)) by pressing the sequence SHIFT BASE 6 - that puts a lower case "h" after the number.

Continuing on:

3. Enter the second number: y^x 9 SIN SHIFT BASE 6

4. Press + (total 17 keystrokes!!!!)



So the 2 main questions are:

1. Why use the SIN, COS, TAN, SQRT-X, y^x and 1/x keys to represent the hex digits A, B, C, D, E and F when there are keys on the calculator labeled "A", "B", "C", "D", "E" and "F"?!?!?!?!?

2. Why do I have to tell the calculator that's currently sitting there in HEX mode that I've entered a HEX number?!?!?!? In fact if I key in a hex number that contains an alpha digit and press enter I get "SYNTAX ERROR"!!!



So in a nutshell - If you're looking for a calculator do to base conversions and arithmetic even occasionally this is *definitely* not for you.

When I found out about the new HP 35s, I knew I had to get one, even though my HP 32sII works just fine. My first HP calculator was the HP 15C, built like a tank and very practical in use. It was the best engineering calculator in the 80's. However, I lost that calculator many years ago.

Although I missed the HP party in San Diego, CA, I purchased the 35s as a sort of "thank you HP" for several reliable, high quality precision tools that they had created through the years. I just received the 35s this week. The key layout reminds me of the older C series calculators and is a positive improvement over the cluttered 32sII key layout. If there is one change I could make on the keyboard layout, it would be to have a separate STO key. To my eyes, the annunciators seem a bit too small on the display. Also, the 35s LCD screen has more reflections than the screen on my 32sII; with indoor lighting, it is more difficult to see the numbers on the 35s.

I'm not sure how to benchmark calculators; however, during some calculations, such as nCr (n=800, r=400), my 32sII found the result faster than the 35s. Other times, such as integration of the bessel function with x=2, the 35s was slightly faster. Again, these were subjective tests, nothing scientific about them.

I doubt I will use the 35s to its full capability (i.e. programmable features) unless I catch the RPN programming bug. Despite my display preferences, I hope the 35s sells well and will encourage HP to design future calculators with the same user-centered design approach and reliability that they have been famous for.

The 35s is a well thought out machine. I like the case that is supplied with it. The manual appears thorough (similar to the 32sII manual) and contains a few grammatical and detail omissions. HP should have provided an electronic copy of the manual on the "bonus" CD video. Perhaps HP will provide a copy for download.

The last time I was excited about a calculator was when I purchased a 15C in 1985. I'm glad I purchased this new 35s and am looking forward to future scientific/engineering RPN calculators from HP.

The HP 35S is inntended to be a tribute to the original HP 35, the first hand held scientific calculator, introduced 35 years ago.

The new calculator is IMO a huge improvement over other recent HP calculators as the keyboard is much more readable and the display contrast is excellent, with adequate size radix indicators. The keyboard has good tactile feedback in the classic HP tradition. The current units cover window on the LCD is very reflective however and needs improvement.

It has 32K of memory, more than adequate for this class of programmable calculator without any external program storage capability or computer hookup ability for program upload and download.

Program structure is directly descended from the HP 32s which places considerable limits on the number of programs that the calculator can hold and prevents giving them longer than single letter names. Program execution speed is about the same as the HP 42s by my testing, adequately fast but not a speed demon. I was personally hoping for program structure closer to that of the classic HP 41C and 42s units.

At least one minor bug has shown up with obtaining the Cosine of angles >= 89.999 degrees but < than 90 degrees. It is a loss of accuracy in the last 3 or so digits of the answer compared to the correct answer. Also no rectangular <> polar conversions are included.

Overall though in RPN mode the unit is the best true RPN Scientific calculator that HP has offered since the HP 32sII and 42s IMO. I am hoping it will eventually be the basis of an upgraded unit that is closer to the 42S in functionality.

I note a couple of reviews have errors in that they do not differentiate between HP's RPN and RPL calculators. ALL RPN calculators will give a different answer to 2 Enter 3 + (5) than they will to 2 Enter 3 Enter + (6) with answers shown in parenthesis. This dates back to the original HP 35 (First RPN) and 28C (First RPL) as I still have one of each in operating condition and checked this.

RPL has an input buffer and the examples given above will both give the answer "5" as the Enter before the "+" moves the input value from the input buffer to the lowest stack location, clearing the input buffer. "+" in RPL will either add the two lowest stack locations or the lowest stack location and the input buffer if it is not clear.

In RPN the Enter duplicates the value in x (the bottom stack register) into the next stack register and + always adds the first and second stack registers. Numbers are input directly into the lowest stack register in RPN calculators.

I own about 15 HP calculators from the oldest to the newest and ALL of the RPN units work one way and the RPL units work the other way.

An RPN Lover