[VA] SRC#005- April, 1st Mean Minichallenge

[Valentin Albillo]

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Hi, Maximilian and Bernd Grubert,

Just some quick comments on your respective posts:

Maximilian Hohmann Wrote:HP-71B with an extra memory module in place of the card reader

One of my physical HP-71B is very similarly fitted, with a 128 Kb RAM module (CMT) in the card reader slot, plus a Math ROM, HP-IL ROM, and 4 Kb RAM modules.

Maximilian Hohmann Wrote:I was at univerisity and not even able to afford an HP-41. The 71B cost over twice as much

How lucky ! It was over three times as much here in Spain, completely unaffordable to me. However, I managed to get one via my then employer, exactly as Thomas Okken did.

Maximilian Hohmann Wrote:I always wonder why so many of them are available on the collector market now, there must have been a lot of wealthy professionals back then who (or whose employer) could afford them.

Nothing of the sort. The UK Government's DHSS (Department of Health and Social Security) ordered thousands of HP-71Bs in the 80's, together with a specialized DHSS ROM, a wand, HP-IL ROM and additional software and hardware. The DHSS ROM turned each HP-71B into a terminal for a one-off file tracking database system, you can read full details here.

In the 90's they became obsolete and were all sold extremely cheaply so the second hand market for the HP-71B was flooded with machines in good working condition fitted with HP-IL ROM, at least one 4 Kb RAM module, and at times even the DHSS ROM itself and/or the wand, but no manuals or leather case or anything else. I bought several back then at US$ 25 each but afterwards I saw them being offered even cheaper and at one HP-fan meeting each attendant was given one for free, as a door prize so to say.

That's the real reason they're so cheap and so aplenty, no need to postulate 'wealthy professionals'.

(PS: Also, I remember I bought four HP-71B via TAS, this time at US$ 50 each, but everyone of them came fitted with a Math ROM (!!), to my immense delight. I doubt they were DHSS machines so: where did they come from ? Another large order by some technical department or something ?)

Maximilian Hohmann Wrote:I wonder what would have happened if HP had brought out a direct successor in the early 1990ies, an HP-72B.

Perhaps HP intended to release a successor but then someone new was hired and made sure to push real hard stack-based models, putting an end to that possibility and so killing for sure any future HP BASIC pocket computers, thus leaving an enormously lucrative market to many very successful SHARP and CASIO models. HP's loss.

(04-12-2019 09:54 PM)Bernd Grubert Wrote:  Sorry for being a bit late and thanks for the interesting challenge. I learned a lot about "mean" calculations (and about HP 15c prgramming). [...] Here is my solution for the HP 15C:

You're welcome, and thanks to you for an excellent solution for the HP-15C, which is very short (just 37 steps) and delivers all correct results to the questions the challenge asked for, so congratulations are in order.

The trick of computing the Geometric Mean by adding logarithms and then a final exponential is perfectly Ok for strictly positive datasets, as in this case, and the precision lost amounts to but a few ulps in the worst case, so it's perfectly acceptable as well.

Thanks again for your interest and for posting such a fine solution. Hope to see you participating in my next challenge or, if you're up to it and would rather not wait, Tier 2 got no solutions at all in my recent S&SMC#24 (still visible in the main page) and it's perfectly within the capabilities of an HP-15C and a keen user like yourself.
Wanna give it a try ?

Best regards to all.
V.
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