HP 40G

HP 39/40 series
Company type	Product line
Industry	Electronics, Calculators
Predecessor	HP 38G
Founded	2000
Founder	Hewlett-Packard
Area served	Worldwide
Products	Graphing calculators (HP 39g, HP 40g, HP 39g+, HP 39gs, HP 40gs, HP 39gII)

HP 39/40 series represents a line of graphing calculators developed by Hewlett-Packard, succeeding the HP 38G. This collection comprises six different models, all offering algebraic input methods and capabilities for numerical analysis, with varying degrees of symbolic computation. Designed primarily for high school learners, each model supports the transfer of APLETs or E-lessons through cable or infrared connections, facilitating enhanced mathematical instruction via graphical and numeric investigation.

HP 39g

Introduced in 2000, the HP 39g (F1906A) features:

CPU: 4 MHz Yorke processor based on the Saturn architecture
Connectivity: Proprietary infrared and serial RS-232
Memory: 256 KB RAM
Display: 131 × 64 pixel resolution
Includes a protective hard cover
Offers limited symbolic equation support

HP 40g

Also released in 2000 alongside the HP 39g, the HP 40g (F1907A) runs on the same operating system but unlocks advanced software features attributable to its distinct hardware.

Its hardware configuration aligns with that of the HP 49G/39G series, featuring a rubber keyboard. Unlike the HP 39g, it incorporates the sophisticated computer algebra system (CAS) from the HP 49G, known as HP CAS. The HP 40g provides an intuitive interface tailored for straightforward mathematical tasks without configuration flags. However, it lacks infrared communication and restricts users to managing only 27 variables. Additional constraints such as a list-based solver limit its use in complex scenarios. The HP 40g is prohibited in several standardized exams like the ACT, though it has been allowed on the SAT since 2019.

Key features include:

Identical specifications to HP 39g except:
Connectivity: No infrared support; serial RS-232
Software: Equipped with an equation editor and enhanced CAS

HP 39g+

Launched in September 2003, the HP 39g+ (F2224A) offers:

CPU: 75 MHz Samsung S3C2410X powered by an ARM920T core
Memory: 256 KB RAM and 1 MB flash storage
Communication: USB Mini-B port compatible with Kermit or XModem protocols, plus IrDA
Power supply: Three AAA batteries with CR2032 battery for memory retention
Display: Resolution of 131×64 pixels
Does not include a hard cover
Symbolic equation capabilities remain limited

Note that despite utilizing an ARM processor, its operating system primarily emulates the Saturn CPU at increased speeds compared to the HP 39g. The CAS functionality present in the HP 40g is entirely omitted rather than merely disabled.

HP 39gs

Released in June 2006, the HP 39gs (F2223A) is equipped with a Samsung S3C2410A CPU running at 75 MHz based on an ARM920T core. It contains 256 KB RAM and offers 1 MB of flash memory for firmware updates. Communication options include USB Mini-B (supporting Kermit or XModem), infrared (IrDA), and a four-pin asynchronous TTL serial port (RS-232 via converter). Powered by four AAA batteries alongside a CR2032 backup battery, it sports a display resolution of 131×64 pixels and comes with a hard cover. Although built on ARM architecture, its OS continues to emulate the Saturn processor at higher clock speeds, ensuring compatibility with earlier HP 39G models.

HP 40gs

Introduced in mid-2006, the HP 40gs (F2225A) is equipped with the same 75 MHz Samsung ARM920T processor and 256 KB of RAM found in the 39gs model, but it distinguishes itself by incorporating 2 MB of flash memory to accommodate advanced CAS applications. Unlike the 39gs, this model does not offer infrared connectivity; however, it includes an equation editor and enhanced computer algebra system features, catering specifically to users who require symbolic algebra functionality.

HP 39gII

The HP 39gII (NW249AA), launched in October 2011, operates on an 80 MHz Freescale STMP3770 processor featuring an ARM926EJ-S core. It contains 256 KB of RAM and a significant 128 MB flash memory, with roughly 240 KB of RAM and up to 105 MB of flash accessible to the user. The device sports a monochrome display with a resolution of 256×128 pixels. Connectivity is provided through a USB-OTG Micro-AB port. Its mathematical libraries were redeveloped in platform-agnostic C code to enable native execution, resulting in improved performance compared to earlier emulation-based approaches. The calculator supports a Pascal-like programming language, which served as a foundation for the HP Prime’s HP PPL, and introduces advanced features such as a 128-level stack and Unicode (UTF-16) compatibility. Two versions exist with minor variations in key labeling.

An upgraded "HP 39gII+" model featuring CAS capabilities was nearly finalized but ultimately discontinued following Freescale’s cessation of the processor’s production. This prompted a comprehensive redesign that led to the release of the more sophisticated HP Prime in 2013, boasting a color touchscreen and enhanced hardware specifications.

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