Text and Images Copyright (C) 2007 Mike Sebastian

The Great Durabrand Mystery

(The title to this article came from a comment made by Tom Lake. It reminded me of the titles of the mystery novels (e.g. “Mystery of the...”) we all read as children.)

The Durabrand 828 is turning out to be a particularly interesting calculator. Not because it is an exceptional calculator - although its twenty dollar selling price is noteworthy - but because there are two versions being sold that are sufficiently different that they should be identified as different models.

An Interesting Email

The mystery came to light when Tom Lake sent an email in early May, 2007, to tell me that his recently purchased Durabrand 828 produced a different forensics result than I had listed in the calculator forensics tables. Further, it calculated its results to a greater number of digits, and it did not have the arcsine bug.

What Tom described sounded like a different calculator. I asked him to send a picture of his Durabrand 828. The next day, he graciously supplied an image. I compared the image of his 828 to my 828. They looked identical.

A Failed Quest

Wanting to have a "new" Durabrand 828, I went to a nearby Walmart, and looked through the 828s in stock looking for differences that might indicate newer inventory from older inventor. Finding none, I purchased an 828. Much to my chagrin, this newly purchased 828 behaved just like my old one.

I was also keeping Viktor Toth informed of what was going on as the Durabrand 828 mystery developed. Viktor went and purchased an 828, which behaved like the two machines I had. With his new 828, Viktor further tried to duplicate what Palmer Hanson described in a detailed review of the 828. Viktor couldn't store some of the graphing functions in a program, and his 828's forensics result was the same as mine. I verified that I could not store graphing functions in a program with my two 828s, too.

I told Tom about having purchased the second Durabrand 828, and having it behave just like my first one. I mentioned Viktor's 828 experience. Tom had also looked at Palmer's review on Viktor's web site, including Viktor's comments, and was intrigued that there appeared to be multiple versions of the 828.

Tom generously offered to send me his 828. I asked him to also send the packaging material so I could study it in detail in the hope of finding some visible packaging difference.

A Package Arrives

A week later, Tom's Durabrand 828 arrived at my house. I examined it and my old 828 carefully for external differences, and found none – externally, they were identical. The packaging looked superficially the same as the packaging of my old 828. The Universal Product Code (UPC) was the same between the two calculators. So, it was time to take a screwdriver to this new 828 to see what was hidden inside.

Inside, it immediately became obvious that there were two versions of the Durabrand 828. The 828 Tom sent me had a different PCB, and a different model number etched on the PCB: "SC-1376." My original 828 had "SC828" etched on the PCB.

A Google search quickly returned the web site of C.T.I. Manufactory (H.K.) Co., Ltd., and a picture of an "SC-1376" calculator sporting the Durabrand logo.

After carefully studying the packaging of the two versions of the Durabrand 828, I identified several subtle differences in the packaging. On the front of the package were several horizontal lines that highlighted various blocks of text. These lines were not quite as wide and were not as brightly colored (more gray and less pink) on the new packaging. Further, some of the background low-contrast artwork was not quite as distinct in the new packaging. These differences were so minor they could be attributed to different printing runs.

Another Quest

The next day after work, I went to a Walmart near my office to test my packaging observations. I picked a Durabrand 828 off the peg and carefully examined the packaging. Were those horizontal lines gray or pink? They almost looked gray, but the lighting in the store wasn't the best. Then I looked at the background art, and sure enough, it didn't look very distinct. I was reasonably sure I had found the SC-1376 version of the Durabrand 828.

I quickly looked at the remaining 828s on the peg, and they all looked to have the new packaging. It appeared this Walmart only had the new version in stock.

I purchased yet another Durabrand 828 and went home.


Once home, I carefully removed this new Durabrand 828 from its packaging. With trepidation, I turned it on, entered the forensics formula "sin-1 cos-1 tan-1 tan cos sin 9" and pressed the EXE key. Almost immediately, the calculator displayed 8.999999998. Success! I had purchased the SC-1376 version of the 828. I knew how to be reasonably certain I was buying the new SC-1376 version of the Durabrand 828!

A New Developments

In early June, Palmer Hansen sent me an email giving the history of his Durabrand 828. His email shrouds the 828 in even greater mystery. He has an SC-1376 version he purchased in early July of 2006, only a month after the Durabrand 828 went on sale at Walmart. So, two versions have have been on sale since shortly after the 828 was introduced. Very strange indeed.

Things get even stranger. Palmer identified an obvious difference between his SC-1376 version and mine. The PCB in his calculator is labeled SC-1376 REV01, while the PCB in mine is labeled SC-1376 REV04. The number I suspect is the part number for the chip is also different. The REV01 PCB has a chip number of YXF6492-1, while the REV04 PCB has a chip number of YXF7685-1. (The chip number on the SC-828 version is labeled as YXF-5191.)

In early August, I received another email from Palmer Hansen. He had purchased another Durabrand 828. And, this 828 was internally different than prior 828s he or I had seen. Coincidently, I had recently purchased a Corner Office ATC-139, and his discription combined with a picture of the interior of his new 828 looked almost identical the ATC-139. There was only one difference - the "SC-1418" model number found in the ATC-139 had been ground off the PCB of his new 828! For a calculator of which we have already seen multiple versions, I cannot imagine what purpose is served by removing the model number from the PCB.

Palmer also reported that the owners manual had been revised again, with a different revision number on the table of contents page, and several corrections throughtout the manual.

More Questions

Both versions, the SC-828 and SC-1376, of the Durabrand 828 are functionally very similar - so similar that they can be manufactured to look identical. (Although, the SC-1376 version lacks a contrast adjustment documented in the mode table printed above the keyboard). The SC-828 version was obviously based on the chip used in the Citizen SRP-320G. The SC-1376 version appears to be a new implementation. Both versions appear to be near-clones of the Casio fx-6300G. In fact, the fx-6300G manual was helpful in my evaluation and understanding of the 828.

There are still many questions about the Durabrand 828.

Why no effort to distinguish between the two versions? Most manufacturers do something to distinguish between versions (other than very minor ROM updates) - even if only to place a "II" after the model number (e.g. "Durabrand 828 II") of the updated version. However, the two versions are externally identical, the Universal Product Codes are the same, the manual is almost identical, and the packaging is clearly intended to be the same.

Why update the Durabrand 828 at all? Assuming no parts supply issues, it doesn't make sense to update a calculator and not identify it as "improved." While the SC-828 version had a few bugs, they were relatively minor from the standpoint of the typical student who would be buying and using this calculator.

The importer, World Import Company, Inc., sells other calculators under its "Le World" trademark. Why not sell this calculator under the Le World trademark? Why sell it under Walmart's Durabrand trademark? Since the Durabrand 828 appeared on Walmart's shelves, new models of Le World branded calculators have appeared on Walmart's shelves, including a financial calculator priced at fifteen dollars - a rather expensive Le World branded calculator.

Some Answers

There are definitely two versions of the Durabrand 828 being sold at Walmart. The old version is internally labeled the "SC828," and the new version is internally labeled the "SC-1376." The new version is more than a mere ROM update. The new version runs faster that the old version. The new version does not have some of the deficiencies of the old version (the arcsin bug, inability to put graphing functions in a program).

Both calculators are manufactured in China and imported by World Import Company, Inc. While we do not know for sure who manufactured the old version, we know the new version is manufactured by C.T.I. Manufactory (H.K.) Co., Ltd. because a picture of the Durabrand 828, complete with the Durabrand logo but identified as the "SC-1376 Scientific Calculator," was found on their web site.

The Two Versions Of The Durabrand 828 Graphing Calculator

Cosmetically, the two versions are identical. The old SC-828 version is on the left, and the new SC-1376 version is on the right.

As previously discussed, the old SC-828 version had several software bugs not present on the new SC-1376 version. Most obvious is the arcsine bug. But, the inability to put graphing commands into a program is also a serious problem.

The old SC-828 version also only had 12 digits of precision, while the new SC-1376 version has 16 digits of precision. However, not all functions in the new version are computed to 16 digits of accuracy. Palmer Hanson's detailed review of the Durabrand 828 discusses these precision issues in some detail, so I will not repeat them here.

The new SC-1376 version omitts the display contrast adjustment function present on the old SC-828 version, even though this function is still documented in the mode table printed above the keyboard.

A quick comparison of the manuals for the two versions also turned up several differences:

Disclaimer: The packaging differences identified in these pictures are based on my own personal observations of the packaging from two old versions and two new versions of the Durabrand 828. The manufacturer may change the packaging without notice. Also see the general disclaimer and terms of use for this web site, which is incorporated by reference into this specific Disclaimer.

This image highlights some of the differences between the packaging of the two versions visible in the store. The horizontal lines around the text blocks are slightly different colors, with the old version being slightly pink while the new version is more gray. The features in the lower left of each package card are the easiest to distinguish in the store.

Click on the image for a larger detailed image.

The PCB of the old SC-828 version of Durabrand 828.

The PCB of the new SC-1376 version of the Durabrand 828.

Note how the conductive lines of the heat seal (right side of image) are different than that on the old version above. This indicates that the LCD was also redesigned.


Last updated September 3, 2007