10B Blue


I just got an HP 10B (not 10B11) off E-Bay. It has the blue shift key and all shift-function lettering is in blue. Serial # is 1D03309585 (made in Indonesia). What is the story on this particualr model? Thought I could figure out manufacture date with serial number, but cannot. Would appreciate any information.

Best wishes



Hi. I believe it's actually a "teal green" rather than a blue as such.

Either way, it is a ghastly horrible color scheme combination that is one of the worst HP ever offered. Who on earth thought this would be a good idea?

It had one of the lowest scores of any contrast scheme HP has ever produced. This was discussed (by me) at the HHC2004 gathering in San Jose.

Link to that presentation:


It was a change made to the 10B color scheme within the last year or so of the original HP10B lifetime. The HP10B was then replaced by the HP10BII.

It's actually somewhat rare.

A similar horrible change was made to the HP32SII around this time as well.


Wow, Gene.

This is a very impressive presentation. Clear. Concise. Solution oriented. I learned a good deal from this one.


Well, there was a lot I learned from giving it.

It was just an idea I had - to compare contrast as the distance formula, just using an XYZ (RGB) score for each color and computing the distance. Greater distance = better contrast.

Of course, it's not quite that simple, but it certainly is a good place to start. It certainly appears that ALL bad color choices HP has made in the past fail my ~200 score requirement on this test.

If only they had asked. :-)


There are many such presentations made at the annual HHC gatherings. If individuals here can attend an HHC meeting, they will find a great group of people and we all learn something. Sometimes, we even get to see toys from HP before they go public. Even better, sometimes we receive toys from HP just for attending.

The next HHC will be in mid-September 2006. Stay tuned!

/commercial off



Hi Gene;

You are right about the contrast....I have an ordinary 10B and my blue or teal 10B sitting next to each other late in the afternoon and the teal is nearly impossible to read. Actually it is totally impossible to read. Thanks so much for the response. Am glad to know this isn't just another knockoff. Your presentation was very impressive.

Best wishes



Gene --

That presentation was a good way to help quantify the principles of good, contrasting colors. The centered yellow-on-dark-faceplate and blue-on-beveled-dark-key scheme utilized by the HP-41, the Voyager series, and the HP-71B was perfection that should never have been tampered with. The blue also suited the light-colored keys on the 71B.

Yellow and blue side-by-side on a dark faceplate also worked well for the HP-34C, HP-20S, HP-21S, and HP-32SII -- until those got replaced by goofy "designer" colors.

Regarding color blindness: I've known that I am color-vision deficient -- probably a carryover from my red/blue colorblind grandfather. I've seen those colored-circle charts before, and the only number I see clearly is the "56" in the middle one.

-- KS


I'd suggest that you take into account the color sensitivity of the human eye. The eye is most sensitive to yellow-green and relatively insensitive to blue. This makes blue legends more difficult to read than might be predicted by models that assume a flat frequency response.

See http://www.amastro.org/at/ot/othcs.html.


yep, those were some of the suggestions made at HHC2004, but this contrast score certainly shows that it would have caught many of the "less than optimal" choices made on some recent calculators.

If any of these efforts at least highlight the problem so that HP notices, it is worthwhile. HP can do the detailed analysis if they are aware of the issue. :-)


Hi Gene.

Read through your presentation and I have to say that I found it er, quite "enlightening". I like the way that you have presented the topic and found also that the "classics" are classics for a reason. I have wondered if it was my old eyes or simply poor contrast selection on HP's part. I'd say I have the answer for the most part.

Good read! Thanks again.



Just to say that Gene's HHC2004 conference presentation (as was the entire conference, and all calc conferences going back over 15 years) were videotaped and copies are available. Check out http://www.pahhc.org/video.htm on the web or send me an email at jakes <at> pahhc <dot> org. I'd be glad to offer Gene's presentation on a DVD if anyone wants a copy.

Jake Schwartz


How does the blue-on-white used on the HP-25 and 29C rate? Can't be very good, either.

Then again, it never bothered me -- most of those legends are simply the inverses of the very easy to read yellow-on-black legends above the keys (and before too long I was typing blind on the machine anyway. ;-) ).

I guess it helped when HP moved away from those multi-colored keyboards. They were pretty (by comparison, I thought the HP-41 was pretty ugly, although it grew on me eventually) but having the number keys be a different color than the rest of the keyboard doesn't really improve usability.

- Thomas


For an even better analysis try using the LAB system. You'll get an even better picture of the contrast using it. The 48s was nearly perfect. Under OpenRPN color standards, I've even made an equally legible purple and green. I am still planning to write an article about the color selection process I went through, some of the most useful information and tools came from NASA.


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