HP-71B

Hewlett-Packard’s HP-71B, introduced in the mid-1980s, was a handheld computer designed for technical professionals, combining a 240-keyword BASIC interpreter with expandable memory and modular peripherals to function as both an advanced calculator and a portable computing platform.

The HP-71B occupied a 7.2 x 1-inch form factor and weighed 12 ounces, marketed as a “pocket-sized package” despite its heft¹. It centered on the Saturn CPU, a proprietary processor using 20-bit addressing to access up to 512K bytes of address space². While base RAM and ROM sizes are absent from documentation, expansion modules offered 4K bytes of RAM and up to 64K bytes of ROM capacity¹. Four internal ports allowed for direct attachment of RAM or ROM modules to the mainframe¹, and the 82401A I/O module eliminated the need for a separate I/O ROM¹.

The machine ran a dedicated operating system and featured a 240-keyword BASIC programming language with internal 15-digit precision math routines¹³. The OPTION statement extended support for system-level configuration, including OPTION BASE for array indexing and OPTION ANGLE for trigonometric units³. Temperature conversion was integrated into the language keywords, supporting Celsius, Fahrenheit, Kelvin, and Rankine units³. Programs written in assembly language reportedly achieved a 20-to-1 speed improvement over interpreted BASIC³.

Software expansion relied on plug-in ROM pacs, including Finance, Circuit Analysis, Surveying, Text Editor, Curve Fit, Math, and FORTH/Assembler¹. The Finance Pac replicated most HP-12C functions with a keyboard layout mirroring the HP-12C’s top row¹. The Circuit Analysis Pac significantly outperformed earlier software on HP’s Series 40 and Series 80 Computers¹. The Surveying Pac introduced a user-friendly file management system for coordinate-based calculations¹. The FORTH/Assembler Pac aimed to attract independent developers, enable custom applications, and offer low-level access to the machine’s architecture¹.

Peripheral expansion was facilitated through the HP-IL (Hewlett-Packard Interface Loop), with optional modules adding a hand-pulled card reader for portable mass storage or enabling communication via RS-232-C/V.24 and HP-IB (IEEE 488) through additional interfaces¹. External keyboards and displays could be connected via HP-IL or adapted interfaces¹. The HP-IL data protocol had precedent in earlier models like the HP-41C¹.

Pricing varied across contemporary publications: $389.95 in one listing⁴, $419.99 in five separate sources^6891113, and $499 in two others⁵⁷¹⁰. The discrepancy remains unexplained in the source material. The HP-71B was positioned alongside other HP models including the HP-41CV, HP-41CX, HP-11C, HP-12C, HP-15C, HP-16C, HP-75C, and HP-75D^456789101113, suggesting a cohesive technical product line.

The HP-71B Internal Design Specification (IDS) documented the system’s hardware, software, and peripherals in detail, indicating a structured engineering approach². Despite its capabilities, the device retained “calculator-like friendliness” to ease adoption among engineers and scientists³. It was explicitly intended for use by technical professionals and could operate as either a high-end algebraic calculator or a full programmable computer¹.

Specifications

References

1. HP Journal 1984-07 (1984)
2. Customize Your HP 28
3. HP Journal 1986-03 (1986)
4. 1986 06 BYTE 11-06 Computers and Music (1986)
5. micro 72 jun 1984[ocr] (1984)
6. 1984 08 BYTE 09-08 Modula-2 (1984)
7. MICRO Vol71-0405 84
8. Compute Issue 055 1984 Dec (1984)
9. micro 74 aug 1984[ocr] (1984)
10. MICRO Vol72-06 84
11. MICRO Vol73-07 84
12. HP Journal 1984-12 (1984)
13. 1986 01 BYTE 11-01 Robotics (1986)