HP 39/40 series

HP 39/40 series
Company type	Product line
Industry	Electronics, Calculators
Predecessor	HP 38G
Founded	2000
Founder	Hewlett-Packard
Fate	Succeeded by HP Prime (2013)
Successor	HP Prime
Headquarters	Palo Alto, United States
Area served	Worldwide
Products	Graphing calculators (HP 39g, HP 40g, HP 39g+, HP 39gs, HP 40gs, HP 39gII)
Owner	Hewlett-Packard
Parent	Hewlett-Packard

HP 39/40 series represents a line of graphing calculators developed by Hewlett-Packard, succeeding the HP 38G. This collection includes six variants that provide algebraic input modes and offer numeric analysis alongside diverse levels of symbolic computation. Designed primarily for high school learners, these calculators facilitate the transfer of APLETs or E-lessons via cable or infrared, thereby supporting enhanced mathematical comprehension through both graphical and numerical methods.

HP 39g

Introduced in 2000, the HP 39g (F1906A) comes equipped with:

CPU: 4 MHz Yorke (Saturn core)
Connectivity: Proprietary infrared and serial RS-232
Memory: 256 KB RAM
Display resolution: 131 × 64 pixels
Includes a protective hard cover
Offers basic symbolic equation capabilities

HP 40g

Also launched in 2000, the HP 40g (F1907A) operates on the same system as the HP 39g but differs in hardware, aligning more closely with the HP 49G/39G lineup and featuring a rubber keyboard. Notable features include incorporation of the sophisticated CAS (Erable) from the HP 49G, absence of infrared communication, and a variable limit capped at 27. Its simplified interface excludes complex flags, making it more accessible though less suitable for advanced users. The HP 40g is prohibited on numerous standardized exams such as the ACT, yet has been permitted on the SAT since 2019.

Core specifications:

Matches HP 39g except for:
Communication: Serial RS-232 only; infrared omitted
Software: Equipped with equation writer and enhanced CAS

HP 39g+

Debuting in September 2003, the HP 39g+ (F2224A) delivers significant hardware improvements:

CPU: 75 MHz Samsung S3C2410X (ARM920T core)
Memory: 256 KB RAM and 1 MB flash storage
Connectivity: USB Mini-B port (compatible with Kermit, XModem), IrDA
Power supply: Three AAA batteries plus CR2032 for memory retention
Screen resolution: 131×64 pixels
No hard cover provided
Limited symbolic equation support

Despite employing an ARM processor, its operating system simulates the Saturn chip at an increased clock speed to ensure compatibility with HP 39g software. The advanced CAS present in the HP 40g is completely removed rather than concealed.

HP 39gs

Released in June 2006, the HP 39gs (F2223A) incorporates a Samsung S3C2410A (ARM920T core) CPU running at 75 MHz, along with 256 KB RAM and 1 MB flash memory. It supports communication through a USB Mini-B port (using Kermit or XModem protocols), infrared (IrDA), and a four-pin asynchronous TTL serial interface. Powered by four AAA batteries with a CR2032 backup battery, it features a display resolution of 131×64 pixels and includes a hard cover. The calculator provides limited symbolic equation functionality and offers flash memory for future firmware upgrades. Its OS emulates the Saturn processor at higher speeds compared to the original HP 39g despite utilizing an ARM CPU.

HP 40gs

The HP 40gs (F2225A), launched mid-2006, shares the same Samsung ARM920T processor running at 75 MHz as the HP 39gs but includes an expanded flash memory capacity of 2 MB to accommodate advanced CAS software. It contains 256 KB RAM but does not support infrared communication. Distinguished by an integrated equation writer and sophisticated computer algebra system (CAS), the HP 40gs offers enhanced symbolic processing capabilities relative to the HP 39gs.

HP 39gII

Launched in October 2011, the HP 39gII (model NW249AA) operates on an 80 MHz Freescale STMP3770 processor featuring an ARM926EJ-S core. It is equipped with 256 KB of RAM and a generous 128 MB of flash storage, of which roughly 240 KB RAM and up to 105 MB flash memory are accessible to users. The device sports a high-resolution monochrome LCD screen with a pixel dimension of 256×128. Connectivity is provided through a USB-OTG Micro-AB interface. The calculator’s BCD arithmetic libraries were redeveloped using native, platform-neutral C code, significantly improving speed compared to earlier emulated System RPL versions. Its programming environment supports a Pascal-style language that served as a forerunner to the HP Prime’s HP PPL, and it features a 128-level stack along with full Unicode (UTF-16) compatibility. Two models exist with minor variations in key labeling.

A more advanced "HP 39gII+" model incorporating CAS functionality was nearly finalized but ultimately discontinued after Freescale ceased production of the processor. This event prompted a redesign that resulted in the release of the more sophisticated HP Prime in 2013, which introduced a color touchscreen and a more powerful CPU.

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