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In my never ending quest to find everything RPN, I have come across a very interesting nonHP RPN calculator, manufactured in the late 1970's by APF Electronics Inc. The company was headquartered in New York, USA, however, the calculators were manufactured in Japan. One of their calculators, the APF mark 55 used RPN, and what makes it interesting is that it introduced builtin hyperbolic functions before HP did on the HP32E. AFAIK this is the only time that a nonHP RPNbased calculator introduced a feature or technology before HP did. I have been trying in vain to locate one of these unique calculators, and wondered if any of you forum participants were lucky enough to include one of them in your collection.
See this photo on Katie's website: APF mark 55
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It's a nice calculator. The buttons looks like they are CanonOEM. I love the red LEDs.
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Interesting! They've actually packed quite a few features into that little thing. Very nice.
It LOOKS, to me, like a rebadged Commodore of that era. I wonder if there was some reciprocal agreement at the time?
thanks,
bruce
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I don't think Commodore had anything like this.
Notice how the INV key serves to reverse just about every key function, such that only half as many explicit items are required. For example, e^x is obtained by typing INV ln. If you want to convert from rectangular (default) to polar coordinates, you type >pol and if you want to convert back from polar to rectangular coordinates, you type INV >pol. Also, you can take any root of a number by preceding the Y^X key with the INV key, e.g. the cube root of 86 is obtained by typing 86 ENT 3 INV Y^X. The INV key was even used to switch between normal and scientific notation and for reversing the direction of unit conversions. The HP65 did something similar with its two shifted yellow keys, one for normal and one to do the inverse.
Pretty clever, I think.
Michael
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So clever, that even TIs use INV from their very beginning...
For me INV is very intuitive. I prefer it over (f) and (g) prefix keys. But I'm a former TI user, so don't take me too seriously. ;)
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Marcus,
No doubt the TI's also had an INV key, however, it was not used to the extent that the APF did. For example, the TI55 used the INV key to invert trig and hyperbolic functions, but not for logarithmic functions. The APF mark 55 had 30 large key buttons, whereas the TI55 had 40 small buttons, and I personally prefer fewer large buttons on any device than many small buttons.
Michael
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Marcus,
We both know TI calculators  the INVkey wasn't always the best choice.
INV SUM+ > SUM .... okay
INV EXC > PI ... you really think that way ;))
INV x! > CSR (Clear stat registers) ... OOPS
To be honest, sometimes I receive customer emails asking "how do I access the 2nd functios of my TI30 STAT!"
Regards,
Joerg
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Quote:
INV SUM+ > SUM .... okay
INV EXC > PI ... you really think that way ;))
INV x! > CSR (Clear stat registers) ... OOPS
At least those are shown on the key faces; but really, they are 2nd functions.
Unfortunately, the original 1976 TI30  and probably the TI30 STAT  do not perform the following perfectlysensible inverse function:
INV 1/x = NOOP (No Operation)
;)
 KS
Edited: 19 Mar 2009, 12:38 a.m.
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On the same vein, I would like a INV NOP (Inverse NoOperation), which will do... everything!! :)
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Isn't there an UNDO on a recent model? Reality is sometimes faster than satire ;)
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Quote:
What about INV CLR ? ;)
On the TI58/58C/59 2nd CLR does yield a clear command but with code 20 instead of code 25.
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Quote:
Notice how the INV key serves to reverse just about every key function, such that only half as many explicit items are required. For example, e^x is obtained by typing INV ln. If you want to convert from rectangular (default) to polar coordinates, you type >pol and if you want to convert back from polar to rectangular coordinates, you type INV >pol. Also, you can take any root of a number by preceding the Y^X key with the INV key, e.g. the cube root of 86 is obtained by typing 86 ENT 3 INV Y^X. The INV key was even used to switch between normal and scientific notation and for reversing the direction of unit conversions. The HP65 did something similar with its two shifted yellow keys, one for normal and one to do the inverse.
The INV key cleans the keyboard, no doubt. It is, however, less versatile than a general shift key (or you get those effects as shown by Jörg). IMHO this was one of the reasons why HP used it on the HP65 only.
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The f^{1} key on the HP 65 is interesting in that it assumes a level of math competency on the part of the user that few other calculator designs have required. The keyboard tells you that f >OCT converts to octal; you have to know (or remember) that f^{1} >OCT means convert to decimal. Same with integer part and fractional part; same with sqrt(x) and x^{2} and ten other functions. I think the designers assumed that, if you could afford the $795 to buy and use the calculator, you could probably remember the correct functions associated with the f^{1} key.
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Quote:
The f^{1} key on the HP 65 is interesting in that it assumes a level of math competency on the part of the user that few other calculator designs have required. ... I think the designers assumed that, if you could afford the $795 to buy and use the calculator, you could probably remember the correct functions associated with the f^{1} key.
Presumably a correct assumption at that time.
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I think the issue is not the cost, but the particular consumer that would buy such a highlytechnical machine. Only a scientist or engineer would be the likely market for such a product.
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Here is Commodore's RPN calculator: (see here)
Notice that it looks nothing like the APF, and is made in Hong Kong instead of Japan. However, it too uses an INV key, however not to the same extent as the APF, although it does one trick that the APF does not. Namely, if you precede the stack rotate key by INV, it reverses the direction of rotation (i.e. roll up instead of roll down). This capability is offered on certain HP calculators, such as the HP15C, where roll up is a g(blue) shift function.
Credit should go to db, Katie W. and T. Spyropoulos for this information on nonHP RPN calculators.
Michael
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Michael;
I have one. It's ok but it's cousinswiththesamechip, the Corvus and Privileg, are better, and at least equal to the HPs they were marketed against (IMHO).
HP didn't have All the firsts. Just most of them.
Elektronika had an RPN with Eprom memory,
National Semiconductor RPNs have a built in stat function that HP never did,
The Robotron RPN combined built in functions that HP didn't. However; no one else even came close to the 41 series (and again IMHO, HP never did again). db
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db,
I see what you mean. The Privileg SR 54 NC also has hyperbolics, and pretty much the same features as the APF. Which National Semiconductor model are you referring to with a stat function, and what function is it? I have the models 4640, 4525, 4615 and 4510, and from what I can tell they are quite mundane. These are all LED models. Did they make any RPN LCD models? I presume you are referring to the Elektronika MK52 with the EEPROM, which was used for backup of programs and data. I have an Elektronika MK61, which is programmable, but does not have EEPROM. I will soon be taking delivery of a mint NIB Sinclair Scientific, which is incrediby crude in comparison with the APF and Privileg.
Thanks for all the good info.
Michael
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Quote:
Which National Semiconductor model are you referring to with a stat function, and what function is it?
The 4510 has an M + x ^{2} function which I discussed in Article 437.
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....as does the Argentine Microcifra 10, and the Unitrex 90sc made in Hong Kong, and the Novus Mathematician from California.
There were a lot of RPN calcs in use back before 99% of math teachers let T.I. tell them how to teach, and before copying an equation verbatim onto a screen and pressing "=" replaced thinking.
BTW: 97.473% of all quoted statistics are made up on the spot.
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FYI, the National Semiconductor/Novus 4510 and Mathematician are one and the same. The National Semiconductor version has nice click buttons, whereas the Novus has crappy spongy buttons.
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Quote:
There were a lot of RPN calcs in use back before 99% of math teachers let T.I. tell them how to teach, and before copying an equation verbatim onto a screen and pressing "=" replaced thinking.
You can believe that if you want to but that's not the way it happened. TI worked with the National Council of Teachers of Mathematics through workshops and conferences and financial support and listened to the teachers. That other company insisted that the teachers do it that conpany's way using a silly system which pretended that parentheses didn't exist in mathematics.
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Ah, the great war between the algebraists and rpners erupts again! It's kind of like the constant battle between the conservatives and liberals, republicans and democrats, appleists and ibmers, DOS and Windows, Coke and Pepsi (my dad worked for Coke and told me that the people who worked for Pepsi were all a bunch of commies). One thing is for sure, nothing good ever comes from these contests and no untruth is left unturned. To quote Rodney King, "can't we all just get along?"
Peace,
Michael
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You forgot the 6502 versus Z80 debate : Apple and Commodore against TRS80 and others.
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Yes, I was aware of the M+x^2 capability of the 4510 and 4615, but db had stated that the NS/Novus calculators have a stat function that HP *never* did have. As you point out in your article, although the HP45 did not have a M+x^2 key, it provided this automatically with the summation key, and also had the mean and standard deviation on the keyboard as well. Still, the NS 4510 was a direct competitor for the HP35, and to that extent it was ahead of the game. Also, it has an x^2 key, M+ and M keys, and can switch between degrees and radians, which are lacking on the HP35.
The NS 4640 is a very strong competitor to the HP45 with all its features, and true units conversions similar to the HP55. Another neat feature is a "clear shifted function", so if you accidentally hit the shift (F) key, you can immediately follow it with the shifted function "CF" to cancel this action. It wasn't until much later that HP introduced toggling of the shift function keys. Unlike the 4510 and 4615, it has a 4level stack, with cyclic roll down. It's only serious flaw is that it has only 3 storage registers, and these are all used by the summation function to store sum x, sum x^2 and n count. The HP45 has 9 storage registers.
Edited: 20 Mar 2009, 12:43 a.m.
