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Calcloverhk En ligne Membre Points: 293 Défis: 4 Message

Issues with HKEAA-approved calculators (Problèmes avec les calculatrices approuvées par HKEAA)

Posté le 07/01/2020 17:01

Casio fx-50FHII was introduced back in 2013, alongside with fx-50FII and fx-3650PII. Like its predecessor, fx-50FHII is just a fx-50FII without the ability to show formulas in order to get approved by H.K.E.A.A. to use in public exams. But since then, Casio do not have any plan to upgrade this calculator (and fx-3650PII) for six years. Does it mean we have already benefited so much from it?

Mainstream calculators in HK

Link: http://www.hkeaa.edu.hk/DocLibrary/IPE/cal/CAL2019.pdf
The above link is the approved calculators in HK. We can see that HKEAA only approved two types of Casio programmable calculators (fx-50F series and fx-3xxxP series) and they became the most commonly used calculators in HK. All of them are not graphic models unlike Graph 35+EII and Graph 90+E.

Issues with fx-50FHII

(Here I will use fx-50FHII as a main example. I do not have fx-3650PII so I will try not to make so much opinions on it)

Issue 1: Old specs from predecessor
fx-50FHII still uses 16 units of dot-matrix display in upper line and 10 units of match-7 display in lower line as same as its predecessor. In fact, Casio has used such display for its fx-50F and fx-3650P lineup for 13 and 17 years respectively. Considering the current prices of them, it is definitely not a great display for them nowadays.

Issue 2: Lacking of calculus
Perhaps it is the most acute disadvantage in this calculator. HK students who elect Mathematics Extended Module 2 - Algebric & Calculus (we call it M2) suffer the most. Most secondary schools in HK recommends fx-50FHII since of its larger bytes for programs. However, if the students choose to study M2, they will need to buy another calculator that has the calculus functions (e.g. fx-3650PII) and this will lead to spend more money just for these calculations. There are calculus programs for fx-50FHII, but they are somehow less accurated. They are not perfect compared to the original feature.

Issue 3: Feature-lacked Casio Basic and poor programming environment
Although fx-50FHII have some advanced commands, but it is still not that useful when you have only four program slots and 680 bytes. Also, this Casio Basic do not support nest. You cannot use any nest-needed commands within any of themself, so you cannot even make an easy-to-understand program involving many structured commands. Besides, it misses Prog, Do~LpWhile, Getkey, etc. It makes the fx-50FHII quite meaningless in programming. Also, fx-50FHII has 6 calculation modes, including COMP, CMPLX, BASE, SD, REG and PGRM mode. During creating a program, you also need to determine one of five modes the program will run in. It is frustrating that users cannot use complex number functions and even the List function in a program which set in COMP mode.

Possible solutions
One of the solutions is to buy fx-3650PII as mentioned. However, if you add the prices of fx-50FHII and fx-3650PII (it is currently ~220 HKD and ~180 HKD respectively according to my research), you will find that spending 400 HKD (€46.2) for only 8 program slots and 1070 bytes in two calculators in total is certainly not ideal for all of us since this price is close to the price of fx-5800P!

I think the best solution is to request Casio for releasing a calculator which at least includes calculus, exam mode and acceptable specs (at around fx-5800P level) within 300~400 HKD budget. This could replace both fx-50FHII and fx-3650PII which exist for years.

Whether it is a market strategy of Casio or not, it is hoped that Casio and HKEAA would work together to develop a better version of approved calculator.

Related link: https://community.casiocalc.org/topic/7932-article-fx-50fhii-is-it-really-enough-for-hk-students-nowadays/


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Zezombye En ligne Rédacteur Points: 1756 Défis: 13 Message

Citer : Posté le 07/01/2020 17:11 | #


Would the french exam mode calculators be allowed? You could try importing one.
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Calcloverhk En ligne Membre Points: 293 Défis: 4 Message

Citer : Posté le 07/01/2020 17:15 | #


@Zezombye:
No, HKEAA prohibits all kinds of graphic calculators.
Calculators fx-50FHII, fx-9750GIII, fx-3650PII

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Lephenixnoir En ligne Administrateur Points: 22869 Défis: 149 Message

Citer : Posté le 07/01/2020 17:58 | #


Interesting. The exam restrictions in Hong Kong are pretty harsh. Also, as you point out, the combined features of the two calculators are waaay below their market price for European standards. Considering that the fx-92 SC+, which is technically a non-programmable calculator, still has 900 bytes of memory for a turtle algorithm with nested structures, this could be made better.

Do you have an idea how large of a market this represents?
Calcloverhk En ligne Membre Points: 293 Défis: 4 Message

Citer : Posté le 08/01/2020 15:56 | #


@Lephenixnoir:
Thank you for your reply.
I take the important part of approved fx series calculators:
Cliquez pour découvrir
Cliquez pour recouvrir
FX-8 FX-10 F FX-39 FX-50 F/FH/FH II
FX-55 FX-61 F FX-68 /B FX-78
FX-82/B/C/D/L/LB/SUPER/SX/W FX-85 /M/N/V FX-100 /A/B/C/V/D FX-115 /M/N/V/D
FX-120 FX-135 FX-140 FX-210
FX-350/A/C/D/H/HA/W FX-451 M FX-500 /A FX-550 /S
FX-570A-/C-/V/D/S FX-911S/SA FX-991 /M/N/V/D/H/S FX-992V/VB/S
FX-3400P FX-3600 P/V/A/PV FX-3650P/P II FX-3800 P
FX-3900PV FX-3950P


As you can see, most of the calculators (except fx-3650PII and fx-50FHII) are pretty old and uncommon.
And yes, I forgot to mention two things: HKEAA seems to prohibit calculators which have dot-matrix display and full 26 alphabets access functions (this is not good). Therefore, fx-92SC+ is not a good choice for me currently (and it's uncommon too).

Exam Mode is really helpful for HK exams. We can enjoy some hign-end features in graphic calclators, while HKEAA can control the students' proper use of calculators.
Calculators fx-50FHII, fx-9750GIII, fx-3650PII

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Lephenixnoir En ligne Administrateur Points: 22869 Défis: 149 Message

Citer : Posté le 08/01/2020 18:55 | #


And yes, I forgot to mention two things: HKEAA seems to prohibit calculators which have dot-matrix display and full 26 alphabets access functions (this is not good).

Oh, now that is extremely restrictive. How can you even program conformtably if you don't have all letters? >_>

Also I assume that calculators with segment-based screens have no more than 2 (maybe 3) rows of text?

Exam Mode is really helpful for HK exams. We can enjoy some hign-end features in graphic calclators, while HKEAA can control the students' proper use of calculators.

Well, if they are able to describe an exam mode to their liking, it would be good I suppose. Have there been any discussions on this topic?
Calcloverhk En ligne Membre Points: 293 Défis: 4 Message

Citer : Posté le 09/01/2020 08:30 | #


@Lephenixnoir:
Lephenixnoir a écrit :
Oh, now that is extremely restrictive. How can you even program conformtably if you don't have all letters? >_>

The restriction is beyond your thought when I reveal more facts of fx-50FHII, but this is what fx-50FHII programming gets really interesting. fx-50FHII doesn't have commands like List [1] or Mat [1]. It only have List x, List y and List Freq. It cannot access the data directly and have to use special calculations.

Although fx-50FHII can only use 6+1 variables (A,B,C,D,X,Y and Ans), it can be increased up to 16 variables in REG Lin Mode (regression in linear, wild right?). In this mode, you have Σx4, Σx3, Σx2y, Σxy, Σy, Σy2, n, Σx and Σx2.

And that's the special method. You will have this program:
Reference: http://webcal.freetzi.com/casio.fx-50FH/tech13.htm
FreqOn: ?→A: ?→B: ?→C: 1 ; 2/-1/(A+B-2C DT:
- 1 ; 2/-1/(A-B DT: 1 , 1 ; C DT: ?→D:
E-50 , 1 ; E50(D-C DT: ?→X: 0 , 1 ; - Σy DT: ?→Y:
; Y DT: , E-50 ; E50(X - Y DT: ?→A: ?→B: ?→C:
E-34 , 0 ; E68(C-Σx2 DT: E-50 ; - E50Σx DT:
; E50B DT: 0 ; -n DT: ; A DT

(/-1/ means x^-1, E means exponential, DT means enter the data given )

The code is incomprehensible in my opinion, but it surprisingly works.
However, it has two drawbacks that the inputted data is not editable (you have to use ClrStat to do so) and the calculation errors occur sometimes especially when inputted data is irrational or recurring decimal number.

Lephenixnoir a écrit :
Also I assume that calculators with segment-based screens have no more than 2 (maybe 3) rows of text?

Yes. According to the approved calculators list, almost all of them have segment display only. fx-50FHII and fx-3650PII are two of the list that has one line of 16-digits dot-matrix and one line of 10-digit 7-segment display.

Ajouté le 09/01/2020 à 12:25 :
Lephenixnoir a écrit :
Well, if they are able to describe an exam mode to their liking, it would be good I suppose. Have there been any discussions on this topic?

Not really, I think. (Currently it seems that only I don't quite satisfied with fx-50FHII)
Webcal was the forum that shares program and opinions in HKEAA-approved calculators, but I didn't create an account here. Now, it seems to be shut down as I can't enter there anymore (only archive).

BTW, there is a bug of irrational number calculation in fx-50FHII:
((√(5)-1)/2)^2
The result is irrational, but when you convert it to fraction, it is convertible and becomes 6765/17711.
Do the graphic calculators have this problem?
Calculators fx-50FHII, fx-9750GIII, fx-3650PII

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Citer : Posté le 10/01/2020 09:46 | #


Ah this hurts indeed. I'm not even sure what this program does. A linear regression?

Even if you can program with that, there is no hope of creating data structures or elegant abstractions... it feels like a command-line with a limited number of commends and no "building blocks".

Yes. According to the approved calculators list, almost all of them have segment display only. fx-50FHII and fx-3650PII are two of the list that has one line of 16-digits dot-matrix and one line of 10-digit 7-segment display.

So obviously no plotting or anything... and programs can only hope to output numbers.

BTW, there is a bug of irrational number calculation in fx-50FHII:
((√(5)-1)/2)^2
The result is irrational, but when you convert it to fraction, it is convertible and becomes 6765/17711.
Do the graphic calculators have this problem?

No, my Graph 75+E prints a decimal approximation, 0.3819660113.
Calcloverhk En ligne Membre Points: 293 Défis: 4 Message

Citer : Posté le 10/01/2020 10:00 | #


Lephenixnoir a écrit :

Even if you can program with that, there is no hope of creating data structures or elegant abstractions... it feels like a command-line with a limited number of commends and no "building blocks".
...
So obviously no plotting or anything... and programs can only hope to output numbers.

For the available commands fx-50FHII has:
?→:◢⇒=≠≥≤><
Goto Lbl
If Then Else IfEnd
While WhileEnd
For To Step Next
...

There are of course more, but their importance are not worth to mention.

Lephenixnoir a écrit :

No, my Graph 75+E prints a decimal approximation, 0.3819660113.

Ok, so that's the fault of fx-50FHII in converting decimal to fraction.

Ajouté le 10/01/2020 à 16:23 :
I summarized the features that HKEAA will prohibit currently:
*Natural Display
*Full 26 alphabets supports
*Graphing

The full dot-matrix display drops from the list because maybe it can exist with Natural Display excluded.
The restrictions above can all be solved by adding Exam Mode.

I saw that there are some faults on Exam Mode.
I think we can add tiny LED to indicate that Exam Mode is enabled?
Or add more security in the storage, for example CASIO can split the disk space for the Exam Mode ROM, and also maybe make it password-protected and encrypt it to furthur prevent from being edited? (This maybe too complicated and even slow down machine, am I right?)

Calcloverhk a écrit :

There are of course more, but their importance are not worth to mention.


The fx-50FHII user's guide, however, mention that While cannot be used with For and vice versa, and If cannot have another If only. It does not mention that If cannot be used with While and vice versa. To put it simply, all nest-needed commands cannot be used with each other.
Calculators fx-50FHII, fx-9750GIII, fx-3650PII

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Citer : Posté le 10/01/2020 20:55 | #


I think we can add tiny LED to indicate that Exam Mode is enabled?

I figure you could, but you would run into the same problems as we have in France related to the organisation of national exams. People watching over the exams must be trained, they must understand the weaknesses to know how and when people are cheating, and there must be enough of them to watch over the blinking LEDs. None of this is easy.

Or add more security in the storage, for example CASIO can split the disk space for the Exam Mode ROM, and also maybe make it password-protected and encrypt it to furthur prevent from being edited? (This maybe too complicated and even slow down machine, am I right?)

Encrypting is not really a good solution here because you can't decrypt on-the-fly to execute. But you could cryptographically sign the OS and put a signature check from a memory which is not editable, ie. the equivalent of the BIOS on the motherboard. But I'm not sure whether such memory even exists. I think the OS of this calculator might just not be editable at all without proper hardware, unsoldering, etc, in which case you can just check the signature at startup.
Calcloverhk En ligne Membre Points: 293 Défis: 4 Message

Citer : Posté le 11/01/2020 15:09 | #


Lephenixnoir a écrit :

Encrypting is not really a good solution here because you can't decrypt on-the-fly to execute. But you could cryptographically sign the OS and put a signature check from a memory which is not editable, ie. the equivalent of the BIOS on the motherboard. But I'm not sure whether such memory even exists. I think the OS of this calculator might just not be editable at all without proper hardware, unsoldering, etc, in which case you can just check the signature at startup.

I see. But why there are still cracked Exam Mode ROM if the OS is non-editable? Isn't there any preventive measures for these actions?
If that's the case, then HKEAA may not want to approve such calculators.
Calculators fx-50FHII, fx-9750GIII, fx-3650PII

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Citer : Posté le 11/01/2020 15:19 | #


The OS may or may not be editable depending on the ROM. Generally ROMs are meant to be read-only (hence the name), but are still reprogrammable with a special circuit on an external board.

If your ROM is not reprogrammable with just the calculator itself, there is no danger of OS modding.

However on French calculators, part of the ROM is used as a filesystem, and the calculator embarks code that can reprogram the ROM on-the-fly. (This has a lot of drawbacks compared to a normal filesystem, but it works anyway.) This system is also used to update the OS from the calculator. Hence it is possible to customize the OS.

Given that HKEAA-approved calculator are extremely simple, I don't think there is anything in the calculator than can be used to reprogram the ROM. Hence, there should be no risk of OS modding, and no need to checksum or cryptographically sign the OS at startup.

Of course in France this is a different story.
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Citer : Posté le 11/01/2020 15:30 | #


That make me feel like in a crossroad. I want some high-end features in the graphic calcs, but they are not approved. I choose a completely safe calculator for exams, but it makes the programming boring and too challenging. What a pity
Calculators fx-50FHII, fx-9750GIII, fx-3650PII

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Citer : Posté le 11/01/2020 15:35 | #


It doesn't seem like there is much chance that exam regulations will change quickly enough in Hong Kong to allow calculators with better features.

If your goal is to program on calculators outside exams, you could use a graphical calculator independent from the one that you use for exams. If you can't get one, there are still regular events on Planète Casio or TI-Planet where you can win one.
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Citer : Posté le 11/01/2020 15:42 | #


Ok, this can be a good goal, I think. But is shipping price too expensive? (HK is much far away from France)

Ajouté le 11/01/2020 à 15:44 :
And Hong Kong has very few place (even none) to let me buy them. (the price includes the shipping part, makes whole model too expensive) The majority is still fx-50FHII and fx-3650PII.
Calculators fx-50FHII, fx-9750GIII, fx-3650PII

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Lephenixnoir En ligne Administrateur Points: 22869 Défis: 149 Message

Citer : Posté le 11/01/2020 15:45 | #


Well, Critor sent one to Sentaro21 last year and also this year, so I guess we could ask him.

@Critor, can you give us an idea of how hard it is to ship calculators to Asia?
Critor Hors ligne Administrateur Points: 2332 Défis: 18 Message

Citer : Posté le 11/01/2020 16:52 | #


@Lephenixnoir

Not complicated. I usually :
- fill the shipment form with a romanized version of the address
- print the real address and stick it on the parcel

Sentaro21 got his parcel each time.
Lephenixnoir En ligne Administrateur Points: 22869 Défis: 149 Message

Citer : Posté le 11/01/2020 17:07 | #


Thanks. How much does it cost, compared to the actual price of the calculator?
Critor Hors ligne Administrateur Points: 2332 Défis: 18 Message
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Citer : Posté le 12/01/2020 09:21 | #


Thanks Critor!

Calcloverhk a écrit :
Ok, this can be a good goal, I think. But is shipping price too expensive? (HK is much far away from France)

Ajouté le 11/01/2020 à 15:44 :
And Hong Kong has very few place (even none) to let me buy them. (the price includes the shipping part, makes whole model too expensive) The majority is still fx-50FHII and fx-3650PII.

Ok, so the calculators usually cost at least 65€ for the simpler graphing models, and more like 85€ for the improved ones, so I think shipping one to you in Hong Kong is still relevant. Shipping costs to France are usually about 10€. I don't remember exactly how it happened with Sentaro, but even if you had to cover the extra cost this would be less than the price range of the fx-3650PII.
Calcloverhk En ligne Membre Points: 293 Défis: 4 Message

Citer : Posté le 12/01/2020 09:52 | #


Hmm... At least 560-730 (price) + 80 (shipping) HKD.
For me, this price is not very worth comparing the price and functions if I choose to buy it for exams mainly.

So which two models did you send to @Sentaro21?
Calculators fx-50FHII, fx-9750GIII, fx-3650PII

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