The HP-55 Enigma

[Matt Agajanian]

Hi all.

I’m trying to make sense of the why, how, where of the HP-55. Armed with two conditional tests, no subroutines, 50 partially merged program steps, what was the intended objective of the 55?

The way I see it—with its function set, it seems a stronger scientific calculator than a programmable.

So, please enlighten me.

Thanks

[Steve Simpkin]

Well despite its limited programming model, it did get you an HP programmable calculator for about the same price as a HP-45 and half the price of a HP-65. It also had a cool (and accurate) timer function and a lot metric conversions which would be very useful when the U.S. changed to the Metric system, which we were assured would only be a matter of days away.

Of course 7 months later the HP-25 came out at half the price of the HP-55. It had 49 fully merged steps and more tests but fewer memories, no timer and no metric conversions. The price of the HP-55 was dropped to $335 about 2 months later.

[Matt Agajanian]

Cool! Kinda makes me appreciate the 55 programs here in the software forums. Yeah. I remember those days. America on metrics—now just a dream.

[toml_12953]

(08-04-2021 05:09 AM)Matt Agajanian Wrote:  Cool! Kinda makes me appreciate the 55 programs here in the software forums. Yeah. I remember those days. America on metrics—now just a dream.

We actually had KPH signs along major highways for a while. Ah, the good old days.

[mfleming]

(08-04-2021 12:31 PM)toml_12953 Wrote:  

(08-04-2021 05:09 AM)Matt Agajanian Wrote:  Cool! Kinda makes me appreciate the 55 programs here in the software forums. Yeah. I remember those days. America on metrics—now just a dream.

We actually had KPH signs along major highways for a while. Ah, the good old days.

Those signs were dropped no doubt because the lettering was reduced to fit the dual markings in the same size sign area, making them difficult to read at distance and speed. I was glad when they went away. But show me something else in the USA these days that isn't dual marked in English/Metric measurements. Other things have gone full metric - can you name one?

[KeithB]

There are still a few kilometer markers on I40 near Needles.

For reasons I have never been able to fathom, in engineering we use US units for everything else *except* temperature which is always in deg C. It must predate me, and I have been in the industry since the early 80's.

[Valentin Albillo]

(08-04-2021 03:07 PM)KeithB Wrote:  For reasons I have never been able to fathom, in engineering we use US units for everything else *except* temperature which is always in deg C.

And this is what happens when Murphy takes the chance.

V.

[Dave Shaffer]

(08-04-2021 02:40 PM)mfleming Wrote:  But show me something else in the USA these days that isn't dual marked in English/Metric measurements.* Other things have gone full metric - can you name one?

Wine bottles!

* I wish writers/editors knew something about significant figures. NASA, say, will report that some asteroid is some 100 meters in size (so one significant figure - at best), and that will appear as 328 feet in some article!

[Namir]

(08-04-2021 04:14 AM)Matt Agajanian Wrote:  Hi all.

I’m trying to make sense of the why, how, where of the HP-55. Armed with two conditional tests, no subroutines, 50 partially merged program steps, what was the intended objective of the 55?

The way I see it—with its function set, it seems a stronger scientific calculator than a programmable.

So, please enlighten me.

Thanks

The HP-55 was my first HP calculator. I used the programming to transform variables for the linear regression. I was also able to push the machine to limit to calculate summation series. As an engineering student I did use the timer in performing experiments in my personal lab (at home) and indeed benefited from the unit conversion features.

My second HP calculator was the hP-67 with its relatively advanced programming features (more steps and merged ones at that, a bit more memory, labels, subroutines, indirect addressing, and program/data I/O on magnetic cards).

Namir

[Gamo]

Another programming functions that HP-55 doesn't have is the [FRAC] and [INT]

So I found that HP use special program algorithm to do [FRAC] and [INT] in the

HP-55 Applications Book

I took part of this program and test on HP-12C here

https://www.hpmuseum.org/forum/thread-14...=%2812C%29

gamo

[Thomas Okken]

(08-04-2021 10:42 PM)Dave Shaffer Wrote:  I wish writers/editors knew something about significant figures. NASA, say, will report that some asteroid is some 100 meters in size (so one significant figure - at best) [...]

The way I learned it, 100 has 3 significant digits. If you wanted to express that number as having only 1 significant digit, you'd write 1x10^2.

[John Garza (3665)]

Funny...

I always thought 100 was 1 significant digit and 100. (with the decimal point) was three.

[John Garza (3665)]

And regarding the original post... I don't see an enigma there.

There was an obvious need for something between the capabilities of the 45 and the 65.
Not to mention the fact that many who wanted a 65 could not afford it.
Not many people walk around today with $5000 laptops - the equivalent of a 65 back then.

Technology advanced and we eventually got the 25. Large organizations have inertia. I'm sure the 25 was not yet a 'sure thing' when they started the 55 project - so it went forward. And even if it were, there was the decision of making some profit from an interim product vs. leaving that gap in the market unserved. Thank rapid technological advancement for the outcome, not bad business planning.

-J

[BruceH]

(08-04-2021 02:40 PM)mfleming Wrote:  But show me something else in the USA these days that isn't dual marked in English/Metric measurements.

Last time I looked, calendars haven't yet changed over to metric time.
:-)

[toml_12953]

(06-18-2023 10:16 PM)BruceH Wrote:  

(08-04-2021 02:40 PM)mfleming Wrote:  But show me something else in the USA these days that isn't dual marked in English/Metric measurements.

Last time I looked, calendars haven't yet changed over to metric time.
:-)

You mean you don't have the 10 day per week calendar yet?

[Matt Agajanian]

(06-18-2023 10:50 PM)toml_12953 Wrote:  

(06-18-2023 10:16 PM)BruceH Wrote:  Last time I looked, calendars haven't yet changed over to metric time.
:-)

You mean you don't have the 10 day per week calendar yet?

Does that mean we’ll still have a five day work-week plus a generous five day weekend?

[Benoit Maag]

Actually, for a few years during the French Revolution, there were 10 day weeks and 3 week months… the 10th day was the rest day of the week. 9 working days in a week must have been unbearable and the system did not last long…

(06-18-2023 10:50 PM)toml_12953 Wrote:  

(06-18-2023 10:16 PM)BruceH Wrote:  Last time I looked, calendars haven't yet changed over to metric time.
:-)

You mean you don't have the 10 day per week calendar yet?

[ijabbott]

(06-28-2023 07:15 AM)Benoit Maag Wrote:  Actually, for a few years during the French Revolution, there were 10 day weeks and 3 week months… the 10th day was the rest day of the week. 9 working days in a week must have been unbearable and the system did not last long…

Also, 10 decimal hours in a day (1 decimal hour = 2.4 hours), with 100 decimal minutes in a decimal hour, and 100 decimal seconds in a decimal minute, so 100000 decimal seconds in a day. 1 decimal second = 0.864 seconds.

[BMH]

In reply to temperatures and significant digits, In the US we say "normal" body temperature is 98.6F and fever is > 100.4F. Which happens to equal 37C and 38C, respectively. But, since F degrees are smaller (by half) and listed in tenths, this implies much more "accurate" guess at what "normal" is. Not only that, but I am quite certain that the (celsius) thermometer used at the time of the initial studies were not all that accurate to begin with.

It is no wonder that people don't understand what significant digits mean, and why they sometimes freak out over insignificant (normal) variation.