HP 39G

HP 39/40 series
Company type	Product line
Industry	Calculator manufacturing
Predecessor	HP 38G
Founded	2000
Founder	Hewlett-Packard
Fate	Successor product line launched (HP Prime)
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 produced by Hewlett-Packard, serving as the successors to the HP 38G. This lineup consists of six distinct models, each supporting algebraic input modes and capable of performing numeric analysis alongside varying degrees of symbolic computation. Designed primarily for high school learners, these calculators facilitate the transfer of APLETs or E-lessons through cable connections or infrared, thereby enriching mathematical education via graphical and numerical methods.

HP 39g

Introduced in 2000, the HP 39g (F1906A) offers the following specifications:

CPU: 4 MHz Yorke (Saturn processor core)
Connectivity: Proprietary infrared and serial RS-232
Memory capacity: 256 KB RAM
Display resolution: 131×64 pixels
Supplied with a protective hard cover
Supports limited symbolic equation solving

HP 40g

Launched concurrently with the HP 39g in 2000, the HP 40g (F1907A) runs on the same operating system but benefits from enhanced software capabilities due to its differing hardware configuration.

Its hardware aligns closely with that of the HP 49G/39G models, featuring a rubberized keyboard. Unlike the HP 39g, it incorporates the sophisticated computer algebra system (CAS) from the HP 49G, known as HP CAS. The HP 40g omits infrared communication and restricts variable storage to 27. Its streamlined interface excludes flags, making it more accessible for basic mathematical tasks while less suitable for complex operations. The calculator is prohibited on certain standardized exams such as the ACT, but has been permitted on the SAT since 2019.

Highlighted features include:

Identical to HP 39g except:
Communication limited to serial RS-232, no infrared support
Enhanced software with equation writer and advanced CAS functionality

HP 39g+

Released in September 2003, the HP 39g+ (F2224A) introduced improvements in processing speed and connectivity options.

Specifications:

CPU: 75 MHz Samsung S3C2410X (ARM920T architecture)
Memory: 256 KB RAM and 1 MB flash storage
Communication interfaces: USB Mini-B port (compatible with Kermit and XModem protocols), IrDA
Power supply: Three AAA batteries plus a CR2032 battery for memory retention
Display: 131×64 pixel resolution
Does not include a hard cover
Limited symbolic equation capability

Despite utilizing an ARM processor, its operating system simulates the Saturn processor at an increased clock speed. Unlike the HP 40g, this model omits rather than conceals the CAS component.

HP 39gs

The HP 39gs (F2223A), introduced in June 2006, is equipped with a 75 MHz Samsung S3C2410A (ARM920T core) CPU, complemented by 256 KB RAM and 1 MB flash memory. Communication options encompass a USB Mini-B port (supporting Kermit and XModem protocols), IrDA infrared, and a four-pin asynchronous TTL serial port (RS-232 available via adapter). 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 device supports limited symbolic equation processing and offers flash memory for future firmware updates. Although based on an ARM processor, its operating system emulates the Saturn chip at higher speeds similarly to the HP 39G.

HP 40gs

Introduced in mid-2006, the HP 40gs (F2225A) utilizes the same 75 MHz Samsung ARM920T processor found in the HP 39gs but is equipped with 2 MB of flash memory to accommodate its sophisticated CAS software. It contains 256 KB of RAM but does not feature infrared communication capabilities. The HP 40gs is distinguished by its equation writer and enhanced computer algebra system functions.

HP 39gII

Debuting in October 2011, the HP 39gII (NW249AA) is powered by an 80 MHz Freescale STMP3770 CPU with an ARM926EJ-S core, offering 256 KB RAM alongside 128 MB flash storage (with roughly 240 KB RAM and up to 105 MB flash accessible to users). It boasts a high-resolution monochrome display at 256×128 pixels and supports USB-OTG Micro-AB connectivity. Its mathematical libraries were completely rewritten in platform-agnostic C for direct execution, resulting in improved speed compared to earlier System RPL emulated code. The device’s Pascal-like programming language served as a foundation for the HP Prime’s HP PPL. Key features include a stack depth of 128 levels and Unicode (UTF-16) support. Two versions are available, differing slightly in their key labels.

An enhanced "HP 39gII+" model featuring CAS was nearly finalized but ultimately discontinued after Freescale ceased production of the processor. This cancellation prompted a redesign with upgraded specifications—including a color touchscreen and a more powerful CPU—which eventually led to the launch of the HP Prime in 2013.

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