TI-Nspire series

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by 122.149.232.10 (talk) at 12:46, 4 February 2015 (→‎TI-Nspire CX and TI-Nspire CX CAS: Updated battery capacity). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

TI-Nspire CX
TypeProgrammable, Graphing
ManufacturerTexas Instruments
IntroducedFebruary 25, 2011
PredecessorTI-Nspire with Touchpad
Calculator
Entry modeD.A.L.
Precision14
Display typeColor LCD
Display size320×240 (3.2″ diagonal)
Programming
Programming language(s)TI-Nspire BASIC, Lua
User memory100 MB
Memory register64 MB
Other
Weight242 grams (8.5 oz)*
Dimensions191 mm × 86 mm × 15 mm (7.5 in × 3.4 in × 0.60 in)
TI-Nspire CX CAS
TypeProgrammable, Graphing, Symbolic
ManufacturerTexas Instruments
IntroducedFebruary 25, 2011
PredecessorTI-Nspire CAS with Touchpad
Calculator
Entry modeD.A.L.
Precision14
Display typeColor LCD
Display size320x240 (3.2″ diagonal)
Programming
Programming language(s)TI-Nspire BASIC, Lua
User memory100 MB
Memory register64 MB
Other
Weight242 grams (8.5 oz)*
Dimensions191 mm × 86 mm × 15 mm (7.5 in × 3.4 in × 0.60 in)
TI-Nspire with Touchpad
TypeProgrammable, Graphing
ManufacturerTexas Instruments
Introduced2010
PredecessorTI-Nspire with Clickpad
SuccessorTI-Nspire CX
Calculator
Entry modeD.A.L.
Precision14
Display typeLCD Dot-matrix
Display size320x240 (3.5″ diagonal)
Programming
Programming language(s)TI-Nspire BASIC, Lua
User memory20 MB
Memory register16 MB
Other
Weight280 grams, 9.9 oz
Dimensions198 mm × 99 mm × 22 mm (7.8 in × 3.9 in × 0.85 in)
TI-Nspire CAS with Touchpad
TypeProgrammable, Graphing, Symbolic
ManufacturerTexas Instruments
Introduced2010
PredecessorTI-Nspire CAS with Clickpad
SuccessorTI-Nspire CX CAS
Calculator
Entry modeD.A.L.
Precision14
Display typeLCD Dot-matrix
Display size320x240 (3.5″ diagonal)
Programming
Programming language(s)TI-Nspire BASIC, Lua
User memory20 MB
Memory register16 MB
Other
Weight280 grams, 9.9 oz
Dimensions198 mm × 99 mm × 22 mm (7.8 in × 3.9 in × 0.85 in)
TI-Nspire with Clickpad
TypeProgrammable, Graphing
ManufacturerTexas Instruments
Introduced2007
Discontinued2010
PredecessorTI-84 Plus
TI-84 Plus Silver Edition
Calculator
Entry modeD.A.L.
Precision14
Display typeLCD Dot-matrix
Display size320x240 (3.5″ diagonal)
Programming
Programming language(s)TI-Nspire BASIC, Lua
User memory20 MB
Memory register16 MB
Other
Weight252 grams, 8.9 oz
Dimensions201 mm × 99 mm × 22 mm (7.9 in × 3.9 in × 0.85 in)
TI-Nspire CAS with Clickpad
File:TI-NspireCAS.jpg
TypeProgrammable, Graphing, Symbolic
ManufacturerTexas Instruments
Introduced2007
Discontinued2010
PredecessorTI-89 Titanium
Voyage 200
SuccessorTI-Nspire CAS with Touchpad
Calculator
Entry modeD.A.L.
Precision14
Display typeLCD Dot-matrix
Display size320x240 (3.5″ diagonal)
Programming
Programming language(s)TI-Nspire BASIC, Lua
User memory20 MB
Memory register16 MB
Other
Weight252 grams, 8.9 oz
Dimensions201 mm × 99 mm × 22 mm (7.9 in × 3.9 in × 0.85 in)

The TI-Nspire product line is a series of graphing calculators developed by Texas Instruments. This line currently includes the TI-Nspire, TI-Nspire CAS, TI-Nspire CX and TI-Nspire CX CAS. There are models aimed for Chinese market, named as TI-Nspire CM-C, TI-Nspire CX-C, TI-Nspire CM-C CAS, TI-Nspire CX-C CAS. There is also software available for Windows and Mac OS X that act in similar ways to the calculators and allow the user to create compatible files. This software either requires a license or can only be used for a limited time. However, Texas Instruments also provides a separate software that can be used for an unlimited time without a license but only allows file transfers and not emulation of the calculator. In 2010, Texas Instruments updated the calculators to the Touchpad versions which come with the Nspire or Nspire CAS computer software and support optional rechargeable batteries. In 2011, TI announced two new models of the TI-Nspire series: Nspire CX and Nspire CX CAS. The main new features are the color screen, rechargeable battery and thinner design.

Handhelds

The TI-Nspire series is completely different from the previous versions of the Texas Instruments's calculators. Because TI wanted the calculator to feel more familiar for new users, the TI-Nspire uses a user interface that is more similar to PCs than regular calculators. It also handles documents in a similar way to PCs. The TI-Nspire was the first to be released in two models; a numeric and CAS version. The numeric is slightly similar in features to the TI-84, except with a bigger and higher resolution screen and a full keyboard. The higher resolution screen makes it possible to draw graphs that are more detailed. The feature that the numeric lacks is the ability to solve algebraic equations such as indefinite integrals and derivatives. To fill in the gap of needing an algebraic calculator, Texas Instruments introduced the second model with the name TI-Nspire CAS, where CAS stands for Computer Algebra System. The CAS is designed for college and university students, giving them the feature of calculating many algebraic equations like the Voyage 200 and TI-89 (which the TI-Nspire was intended to replace). However, the Nspire does lack part of the ability of programming and installing additional apps that the previous models had, although a limited version of TI-BASIC is supported, along with Lua in later versions. C and assembly are only possible through the jailbreaking program Ndless.

Both the Nspire and Nspire CAS calculators have 16 MB of NAND Flash, 20 MB of SDRAM, and 512 KB of NOR Flash. The NAND Flash contains the operating system and saved documents and is not executable. The SDRAM likely contains an uncompressed version of the OS, and a copy of all active documents. The NOR Flash contains boot instructions for loading the operating system.

The Nspire family doesn't contain a backup battery (like all previous models) so when a battery is removed, the SDRAM content is deleted, hence the need to load the operating system and file structure from the NAND Flash to the SDRAM, causing a longer loading time.

TI-Nspire

The standard TI-Nspire calculator is comparable to the TI-84 Plus in features and functionality. It features a TI-84 mode by way of a replaceable snap-in keypad (included) and contains a TI-84 Plus emulator. The likely target of this is secondary schools that make use of the TI-84 Plus currently or have textbooks that cover the TI-83 (Plus) and TI-84 Plus lines, and to allow them to transition to the TI-Nspire line more easily.

Because the TI-Nspire lacks a QWERTY keyboard, it is acceptable for use on the PSAT, SAT,[1] SAT II, ACT,[2] AP, and IB Exams. It should be noted, however, that the CAS version is NOT allowed on the ACT.

TI-Nspire CAS

The TI-Nspire CAS calculator is capable of displaying and evaluating values symbolically, not just as floating-point numbers. It includes algebraic functions such as a symbolic differential equation solver: deSolve(...), the complex eigenvectors of a matrix: eigVc(...), as well as calculus based functions, including limits, derivatives, and integrals. For this reason, the TI-Nspire CAS is more comparable to the TI-89 Titanium and Voyage 200 than to other calculators. Its likely targets are college students and universities. Unlike the TI-Nspire, it is not compatible with the snap-in TI-84 Plus keypad. It is accepted in the SAT and AP exams (without a QWERTY keyboard) but not in the ACT[2] or IB. The body color is grey.

TI-Nspire Touchpad

The special version of the TI-Nspire Touchpad for schools

On March 8, 2010, Texas Instruments announced the new TI-Nspire Touchpad and TI-Nspire CAS Touchpad graphing calculators. In the United States the new calculator was listed on the TI website as a complement to the TI-Nspire with Clickpad while in some other countries, the calculator was introduced as a successor to the previous model. The calculators were released alongside the OS 2.0 update, which featured a number of updates to the user interface and new functions.

The keyboards on the touchpad keypads featured a different and less crowded key layout along with the touchpad, which is used for navigation. The touchpad keypads are also compatible with older calculators that are running OS 2.0 or newer. The new calculators that were shipped with touchpad keypads supported an optional rechargeable battery. The second generation is also available in two models, the TI-Nspire Touchpad and TI-Nspire CAS Touchpad, and each model has maintained the color of itself, with the normal one being white and black while the CAS is black and gray.

TI-Nspire Touchpad EZ-Spot

To reduce theft of school-owned TI-Nspire calculators, Texas Instruments also introduced the EZ-Spot Teacher Packs with a bright, easy-to-spot, "school bus yellow" frame and slide case. The hardware of both versions are the same, with the only differences being cosmetic. The TI-Nspire calculators that were released after the touchpad Nspires also have EZ-Spot versions.

TI-Nspire CX and TI-Nspire CX CAS

The TI-Nspire CX and CX CAS are the latest update to the TI-Nspire series. They have a thinner design with a thickness of 1.57 cm (almost half of the TI-89), a 1200 mAh rechargeable battery (wall adapter is included in the American retail package), a 320 by 240 pixel full color backlit display (3.2" diagonal), and OS 3.0 which includes features such as 3D graphing.[3]

Texas Instruments currently lists the TI-Nspire CX at $165 and the CX CAS at $175 on their US online store.[4] The CX series were released in the same time frame as the Casio Prizm,[5] Casio's color screen graphing calculator with similar features, priced at $130. The TI-Nspire CX series differ from all previous TI graphing calculator models in that the CX series are the first to use a rechargeable 1060 mAh Lithium-Ion battery (upgraded to 1200 mAh in 2014 rev., previous models required AAA batteries). Retail packages include an AC adapter for charging the battery; however, the device can also be charged via a PC USB connection. TI claims that the battery requires four hours to charge, that a full charge powers the device for up to two weeks under normal daily use, and that the battery should last up to 3 years before it requires replacement. The battery is user-replaceable and can be purchased via the TI education online store for $15 in the United States.[3]

With the exception of interchangeable TI-84 keypads, the CX series retain all features of the previous TI-Nspire models. The colors of the calculator are still the same as those of the TI-Nspire models; the CX is white and dark blue, while the CX CAS is gray and black. The external connectors have changed slightly. The mini-USB port, located at the center of the top of the TI-Nspire series, has moved to the right on the CX series. On the CX series, TI added a second port immediately left of the mini-USB port, for a new wireless module. The new wireless TI-Nspire Navigator adapter, which allows teachers to monitor students and send files, is not compatible with the previous TI-Nspire models. The third port, located at the bottom of the handheld, is for the TI Charging Dock and Lab Cradle. The keypad layout is very similar to that of the TI-Nspire Touchpad.

Both models have 100 MB of user memory and 64 MB of RAM. The retail package comes in a plastic blister case and doesn't have the full manual, while the teachers edition comes in a box with a TI-Nspire CX poster for classrooms and the full manual (in English and French in the US). Both devices ship with the student/teacher software for Windows/Mac OS X. According to Texas Instruments, The CX is accepted in SAT, IB, AP and ACT and the CX CAS only on SAT and AP.

Chinese Versions

Four models aimed for Chinese market were launched, with specialized features. All four models have Chinese labeled keyboards. The CX-C and CX-C CAS models are similar to CX and CX CAS, but included a concise Chinese-English dictionary. The CM-C and CM-C CAS are cheaper, featured a more stream-lined design, but have only 32MB of RAM and no port for the wireless module. The systems of the Chinese versions are not interchangeable with those of the international models.

TI-Nspire Software

The TI-Nspire desktop application is the companion to the TI-Nspire handhelds, allowing the user to create, edit, and save documents in the same manner as on the TI-Nspire. The TI-Nspire PC desktop application software emulates of all the features of TI-Nspire handheld; however, desktop application execution is usually (depending on the architecture of the PC) considerably faster than the TI-Nspire handheld. The aforementioned performance difference is mostly due to hardware architecture and desktop application/device firmware compilation differences. The user may create and modify documents on either the TI device or desktop application, and the user may also seamlessly exchange files between the device and the desktop application. The TI Nspire desktop application currently consists of four versions: TI-Nspire Student software and the TI-Nspire Teacher software, each having a numeric and CAS version.

OS versions

  • 1.0.491 (June 2006) - Prototypes
  • 1.0.526 (September 2006) - Prototypes
  • 1.1.8916 (Late 2006 / Early 2007) - Prototypes
  • 1.1.9170 (May 7, 2007)
  • 1.1.9253 (non-CAS version)
  • 1.2.2394 (August 30, 2007)
  • 1.3.2437 (January 8, 2008)
  • 1.4.11643 (July 9, 2008)
  • 1.6.4295 (October 29, 2008, released December 9, 2008)
  • 1.7.2741 (May 19, 2009, released June 6, 2009)
  • 1.8 (build 80) Dev (Late 2009) - Prototypes
  • 2.0.0.1188 (March 5, 2010)
  • 2.0.1.60 (May 3, 2010)
  • 2.1.0.631 (July 17, 2010)
  • 3.0.1.1753 (April 2011)
  • 3.0.2.1791 (May 2011)
  • 3.1.0.392 (September 7, 2011)
  • 3.2.0.1212 (June 2012)
  • 3.2.0.1219 (June 2012)
  • 3.2.3.1233 (December 2012)
  • 3.6.0.546 (December 2013)
  • 3.6.0.550 (February 2014)
  • 3.9.0.461
  • 3.9.0.463 (June 2014)

The current TI-Nspire calculators are now running the OS version 3.9.0.463, released in June 2014. The operating system has been updated frequently since 2007 (partly due to bugs and missing functions, and also to patch jailbreak exploits), one year after its release in 2006. Version 2.0 and 3.0 were major upgrades that added many features.

Added features in OS 2.0

  • Scratchpad (Easily and quickly use a calculator and graph)
  • New, more organized home screen
  • Calculator application changes
    • Solving of systems of equations (linear or non-linear)
    • Complex and real roots of polynomials
    • Derivative at a point
    • Remainder, quotient, coefficients, and degree of polynomials
    • Greatest common divisor
    • Central difference quotient with steps
    • Creation of a zero matrix
  • New programming capabilities
    • Ability to separate a programming page from a calculator page
    • Request and RequestStr I/O functions
    • Output text
  • Graphs application changes
    • Can toggle table of values
    • Can hide object selection guides
    • Custom sequence graphs
    • Zoom to decimal
    • Analyze Graph menu
      • Zero
      • Minimum
      • Maximum
      • Intersection
      • Inflection
      • dy/dx
      • Integral
  • New geometry application is simply a graphing application that can only make shapes
  • Data and Statistics application changes
    • Ability to add X and Y variables with frequency
  • Notes application changes
    • Calculations in the Notes application,
  • New graph settings page

Added features in OS 3.0

Images can be included in TI-Nspire documents using the computer software. They can then be displayed on the Nspire calculators and in full color on the Nspire CX calculators. Graphs can be drawn on top of the images. A data collection application is included with the OS, for use with the Lab Cradle. 3D graphing is supported, as well as differential equations. Other features were also added, including improvements to functions that are related to statistics.[6] OS 3.0 also adds the ability to run programs that are written in Lua.[7][8] OS 3.0.1 introduced a number of bugs,[9] but most of these have been fixed as of 3.0.2.[10] In OS 3.2, conic equations in standard formats can be graphed and a new chemistry feature, Chem Box, allows users to write chemical notations.[11] OS 3.2 also saw the inclusion of the Chipmunk physics engine for use in Lua programs.[12] In OS 3.9, the area between curves can now be calculated on the graph bar.[13]

Other features

One feature includes a periodic table, useful for chemistry classes. As with some other TI graphing calculators, the TI-Nspire can be used with sensors to deal with the real world (data acquisition) such as Vernier EasyTemp, Vernier Go! Motion, Vernier Go! Temp, or Texas Instruments CBR2 motion detector.[14][15][16] In addition, it has been hacked to run homebrew software.[17] With the release of OS 3.0, the Lua scripting language is supported, allowing 3rd party programs to be run without the need of exploits.[7][8] There are currently more than 50 third-party programs and functions for the Nspire that introduce new functionality, like Laplace Transform, Fourier Transform and 3rd and 4th degree differential equations, that aren't included by default.[18]

Lab Cradle

The TI-Nspire Lab Cradle continues the idea of the original Calculator-Based Laboratory System (CBL™) introduced already in 1994, a portable and versatile data collection device for math and science. The CBL system was replaced in 1999 with its successor CBL 2, featuring three analog inputs and an ultrasonic motion detector input to connect the Calculator-Based Ranger, CBR and its successor CBR 2. The TI-Nspire Lab Cradle sports three analog inputs with a sampling rate of up to 100,000 samples per second and two digital sensor ports. The integrated 32 megabytes of storage space allows for handling large amounts of data.

The TI-Nspire Lab Cradle is powered by the TI-Nspire rechargeable battery and support three different charging options: wall adapter, USB cable to computer and TI-Nspire Cradle Charging Bay. The TI-Nspire Lab Cradle being marketed by Texas Instruments was developed as part of an ongoing business alliance between TI and Vernier Software of Portland, Oregon.

TI-Nspire Navigator System

The Navigator system allows teachers to connect a network of TI-Nspire calculators to a computer through the TI-Nspire Access Point and TI-Nspire Navigator Wireless Cradles. The system includes the TI-Nspire Cradle Charging Bay and the main system which looks like a wireless router. The Navigator system was first available when the first generation Nspires were launched, but when the TI-Nspire CX and CX CAS were released, a new wireless adapter was announced that is smaller but not compatible with the TI-Nspire and TI-Nspire Touchpad.

Press-to-Test

Press-to-Test is a feature that restricts access to the user's documents and certain features of the calculator for a limited time. Its intended purpose is to prevent cheating on tests and exams. Press-to-Test is enabled by pressing a certain button combination when turning on the calculator. The features that are blocked (for example 3D graphs and drag & drop for graphs) can be selectively enabled, but access to existing documents is always prohibited. When the handheld is running in Press-to-Test mode, a LED on top of it blinks to indicate that Press-to-Test hasn't been disabled. Press-to-Test can only be disabled by connecting to another calculator or a computer with TI-Nspire compatible software installed. Removing the batteries or pressing the reset button will not disable it.

Ndless

Developed initially by Olivier Armand and Geoffrey Anneheim and released in February 2010 for the Clickpad handheld,[19] Ndless (alternatively stylized Ndl3ss) is a third-party jailbreak for the TI-Nspire calculators that allows native programs, such as C, C++ and ARM assembly programs, to run. Organizations such as Omnimaga and TI-Planet promoted Ndless and built a community around Ndless and Ndless programs. With Ndless, low-level operations can be accomplished, for example overclocking, allowing the handheld devices to run faster. Downgrade prevention can be defeated as well. In addition, Game Boy, Game Boy Advance, and Nintendo Entertainment System emulators exist for the handhelds with Ndless.[20] Major Ndless-powered programs also include a port of the game Doom.[21] Unlike Lua scripts, which are supported by Texas Instruments,[22] Ndless is actively counteracted by TI. Each subsequent OS attempts to block Ndless from operating.[23]

Voyage 200 vs. TI-Nspire CAS

TI-Nspire CAS has some advantages over the Voyage 200 or TI-89:

  • Larger and higher resolution screen, color LCD in the CX models, compared to the Voyage, making graphs more detailed, especially in 3D.
  • The Nspire user interface has more similarities to traditional PC interfaces, for example: To copy, press Ctrl+C, like in a computer. This simplifies the learning curve for some users. The V200 also works like this.
  • Students create and save all of their work as documents with notes, thus enabling teachers to see problem-solving techniques and assess individual student understanding. These documents can be sent to other handhelds, or to a PC, where they can be edited or printed using the Nspire software.
  • Symbolic mathematics templates on the input as well as output, or "PrettyPrint" - the ability to show the results as they would normally be written. The Voyage 200 and TI-89 did this to output, while input remained standard.
  • More powerful compared to the Voyage 200. The Nspire can handle bigger matrices, a broader selection of equations and functions, all more quickly, since the processor is more powerful and more RAM is available.
  • Space – the new CX models have up to 100 MB of user memory and the grayscale Nspires had about 20 MB of user memory, compared to the TI-89 Titanium and Voyage 200's 188 KB RAM and 2.7 MB Flash ROM.
  • Graphing has been updated, giving users the option to derive or integrate a function in-graph.
  • There is a spreadsheet function which is similar to a list editor. Data from spreadsheets and lists can be analyzed and graphed.
  • Data and statistics functions have been improved.
  • It is possible to view several pages of data at once, effectively splitting the screen between each page. The user can interact with any portion at a time.
  • The newer versions of the Nspire OS are capable of opening files that contain images.
  • The Nspire has a new Vernier DataQuest function which can be used to collect data from any sensors connected to the Lab Cradle, which allows up to 5 sensors, or one sensor probe can be connected via USB port on top of the handheld.

However, there are some things that the TI-Nspire lacks when compared to the Voyage 200 and TI-89:

  • The V200 and TI-89 can solve many algebraic equations, and data input on the TI-89 can be easier for the user than the Nspire.
  • All versions of the V200 OS can graph in 3D while this was introduced in an OS update for the Nspire.
  • The TI-89 and V200 have better programming capabilities – their built-in language has more I/O and graphics commands, and they also support native assembly programming. The Nspire only has C and assembly support through the jailbreaking program Ndless.
  • Third-party apps using native code (like ME*Pro and the Symbolic Math Guide (SMG)) are not available on the TI-Nspire, but newer versions of the OS can run Lua scripts.
  • The Voyage features a full QWERTY keyboard, which makes programming and other text input easier for the user. However, some tests do not allow calculators with a QWERTY keyboard.[2][24]

See also

References

  1. ^ "SAT - Calculator Policy". The College Board. Retrieved 5 March 2013.
  2. ^ a b c "ACT - Can I use a calculator?". ACT, Inc. Retrieved 5 March 2013.
  3. ^ a b "TI-Nspire™ CX CAS Handheld". Retrieved 28 June 2013.
  4. ^ "Texas Instruments Online Store". Retrieved 28 June 2013.
  5. ^ Casio Education: PRIZM - Graphing Calculator
  6. ^ "TI-Nspire™ Technology Version 3.0 Release Notes" (PDF). Texas Instruments. April 2011. Retrieved 1 August 2011.
  7. ^ a b "Lua Programming Environment on the TI-Nspire Found". ticalc.org. Retrieved 18 July 2011.
  8. ^ a b "TI-Nspire™ Technology - Lua Scripting". Texas Instruments. Retrieved 21 August 2011.
  9. ^ "Beware Installing TI-Nspire OS v.3". ticalc.org. Retrieved 21 August 2011.
  10. ^ "TI-Nspire OS 3.0.2 Released". ticalc.org. Retrieved 21 August 2011.
  11. ^ "TI-Nspire™ Technology Version 3.2 Release Notes" (PDF). education.ti.com. Retrieved 11 June 2012.
  12. ^ http://www.inspired-lua.org/upload/TI-Nspire_Scripting_API_Reference_Guide_EN.pdf
  13. ^ "What's New in Version 3.9". education.ti.com. Texas Instruments. Retrieved 7 July 2014.
  14. ^ Vernier Software & Technology Global Gateway
  15. ^ CBR 2 by Texas Instruments -US and Canada
  16. ^ Data Collection - TI-Nspire.com by Texas Instruments
  17. ^ "Nspire Models Opened to Third-Party Development". ticalc.org. Retrieved 31 August 2010.
  18. ^ "TI-Nspire BASIC Math Programs". ticalc.org. Retrieved 28 June 2013.
  19. ^ "Nspire Models Opened to Third-Party Development". http://www.ticalc.org/. Retrieved 10 June 2014. {{cite web}}: External link in |website= (help)
  20. ^ "Ndless for TI-Nspire". Retrieved 3 June 2014.
  21. ^ Sheffer, Sam. "TI-Nspire calculator: yes, it plays Doom". http://www.engadget.com/. Retrieved 10 June 2014. {{cite web}}: External link in |website= (help)
  22. ^ "Lua Scripting in TI-Nspire™". http://www.ti.com/. Retrieved 13 June 2014. {{cite web}}: External link in |website= (help)
  23. ^ "TI vs. Calculator Hobbyists, Again". http://beta.slashdot.org/. Retrieved 13 June 2014. {{cite web}}: External link in |website= (help)
  24. ^ "SAT Test Day Checklist - Bring Your Admission Ticket, Calculator, and more". College Board. Retrieved 12-09-2011. {{cite web}}: Check date values in: |accessdate= (help)

External links