Not RPN or HP, but interesting.


I have seen Aurora calculators at discount stores and supermarkets for years. They are typically very cheaply made, 4 functions plus percent, and sold at a low end price - lower than a cheap TI or Casio.

In a California electronics store, I saw an Aurora scientific calculator, model SC150X. Since it was only $5.99, I decided to pick one up just to see what they offered. First, it is a very small clamshell design - smaller than any scientific calculator I have seen in current production. (I do have an old credit card sized solar calc, but they are out of production.) The plastic feels like the cheapest material known to mankind, so I cannot imagine that this would hold up to any sort of rough treatment.

However, the features are remarkably good. It has the trig functions and their inverses. It also has logs (natural and base 10), and their corresponding exponentials. Of course, there is an x^2 and a square root key. There is also a y^x and even a cube root key. Interestingly, the cube root key does allow correct computation of the cube root of negative numbers - I have seen others which do not. It has single variable statistics, polar to rectangular conversions, factorial (integer only), degrees to degrees-minutes-seconds, and a random number generattor. It also operates in hex, binary, and octal in addition to decimal.

Now, it's a bit confusing to use (to me) because it is algebraic and operation of R<->P and similar things are not intuitive in that system, but . . . overall, I am pretty impressed. For $5.99 in a size and weight that can truly disappear in a shirt pocket, it's pretty impressive.

Now, back to HP - where did I put my 42S??




I have seen these around. Not bad for $5-$6. Keyboard layout seems similar to Tozai ATC828 which is based on a Toshiba calc chip, IIRC. (you can see and do a 'forensic test' of numeric processing to identify what chip/calc you have.)

The smallest sci calc currently on the market is prob the TI-25X. Think of a TI-30 (with 5x8 keyboard) shrunk down to a-tad-larger-than-credit-card size.

In the early 80s Casio made the FX-28 (48?) [landscape KB orientation] and FX-68 (portrait orientation) credit card sci calcs.

Bill Wiese
San Jose, CA


The credit-card sized scientific calculator which I have is a Radio Shack EC-4009, which is a re-branded Casio - probably the FX-28 you mentioned. RPN would make it better, but I would buy another if these were still made. It's nice to have a scientific which is so small. I used to carry it in my organizer all the time.


I found your calculator on the net with the part number you gave : it's a gift for customers who buy for 50$!! :

I bought an AUREX SC-109P for 10$ at wal mart: it have 20 physical constants, 28 memories, 38 built in function, logical operation, hex-dec-oct-bin, Dot matrix LCD, 2 lines diaplay etc, etc plus guest what a 100 steps keystrokes programmable calculator. This package in 1970's cost 100 times more!!!

Why our more important manufacturer like HP, TI, sharp or casio don't manufacture programmable calculator except graphing one? I'm sure it just cost a few $ more to get a calculator be programmable, even less than 1$ per unit. Why not copying the HP41 with modern parts and sell them for 20$ - just copy the ROM and put it in a Aurex or Aurora?



wouldn't the SW copyright rise the price too much?

Just a question.

(I'd like to see an HP41CX with the advantage module and a RAM bank...)


I picked up an 'ABACUS 268' calculator that sells for $7. Although non-programmable and non-RPN, it has a wealth of functions, incl. e.g. statistics, binaries, ln and log, hypertrig and complexes. I'm very much into complexes on my 48SX, but I can't figure out how it works on this one - I've tried and tried, nothing significant happens... (The instructions are for the birds. They only say that CPLX is used for complex numbers!) If any of you have this 'ABACUS 268' and have figured out the CPLX function, please let me know! BTW it is so small and slim that it practically disappears in my shirt pocket. Seems to be fairly well made too.


I believe I may have the cheapest scientific calculator yet. I paid $1.49 for what appears to be a Chinese copy of the Sharp EL-506. It even says EL-506P on the front. It includes all of the usual scientific functions: trig including hyperbolic; logs; coordinate conversions; floating and engineering notation; complex numbers; random numbers; binary, octal, hex and decimal numbers; statistics; degrees, radians and grad modes; memory safeguard (turn the power off and the memory register retains its contents), etc. It displays up to 10 digits in normal format and 8 digits with a 2 digit exponent. It even came with a Operation Manual and a thin plastic folding case. It works quite well although it does not compare to my HP15C.

Possibly Related Threads…
Thread Author Replies Views Last Post
  HP-80 History, Design and Interesting Facts BShoring 1 1,316 11-30-2013, 08:50 AM
Last Post: Xavier A. (Brazil)
  [PRIME] RPN: another attempt at returning more than one value to the RPN stack Marcus von Cube, Germany 5 2,424 11-05-2013, 02:44 AM
Last Post: Marcus von Cube, Germany
  Interesting Base Conversions - Porting a 1975 HP 25 Program to the HP 35S Eddie W. Shore 1 1,319 10-13-2013, 07:49 PM
Last Post: BruceH
  Interesting TI Nspire CAS CX programming features Namir 5 1,889 04-15-2012, 04:11 PM
Last Post: Namir
  An interesting riddle Don Shepherd 15 3,920 03-13-2012, 11:54 PM
Last Post: Don Shepherd
  Interesting patterns for HP-42S Tom Grydeland 6 2,234 03-07-2012, 07:40 AM
Last Post: Tom Grydeland
  Interesting Book with lots of HP info Dave F 2 1,458 02-17-2012, 03:09 AM
Last Post: Nick_S
  OT but interesting; a new calendar proposal Don Shepherd 12 3,458 01-02-2012, 04:32 PM
Last Post: Don Shepherd
  Interesting AT&T hp-15C Gerardo Rincon 13 3,283 11-28-2011, 11:11 AM
Last Post: Lincoln R.
  An interesting challenge Don Shepherd 10 3,088 11-19-2011, 05:04 AM
Last Post: Oliver Unter Ecker

Forum Jump: