Hewlett-Packard 80 & 45  
Written by Accutron on 2015-06-03  

Devices included in this entry:

Hewlett-Packard 80 Financial Calculator
Hewlett-Packard 45 Advanced Scientific Calculator (pictured in thumbnail)


In 1972, Hewlett-Packard introduced the HP-35 scientific calculator, fundamentally altering the way humans would perform higher mathematics for the first time in 450 years. Commercial digital computers and calculators had been available for over two decades, but systems were large, expensive and limited in availability. Minicomputers were in their heyday, but computer and scientific calculator access was still limited primarily to governments, businesses and educational institutions. The HP-35 single-handedly democratized computation. It was, in every meaningful sense, the world's first personal computer and the world's first handheld computer.

Despite its revolutionary capabilities, the HP-35 did not fully implement a number of features that would soon become common on HP scientific calculators. The HP-35 served as a sort of large-scale production prototype, establishing the architecture and construction methods that would be used in subsequent calculators, as well as acclimating HP to the vagaries of manufacturing and selling a high-volume consumer product for the first time.

Exactly one year after the launch of the HP-35, Hewlett-Packard introduced the HP-80, a financial calculator built on the same architecture and mechanical specification as the HP-35. While the HP-35 was equipped with three ROMs, the HP-80's microprogrammed space was expanded to seven ROMs, all contained within a single custom hybrid IC package. The HP-80 also introduced the shift key, a revolutionary improvement in key-per-function calculation, which doubled (approximately) the the number of functions accessible to the user for any given key count. Since the HP-80, shift and alpha keys have become ubiquitous on scientific and financial calculators from all manufacturers.

Three months after the HP-80, Hewlett-Packard introduced the HP-45, their second scientific calculator. The HP-45 was an upgraded HP-35 with a greatly expanded ROM and ten 56-bit storage registers. As the HP-45 was HP's first mature scientific calculator, it introduced a range of important new functions. The HP-45 was the first HP handheld calculator with storage registers, the first with a formatted display, the first with a LAST X register and the first handheld scientific calculator with a shift key. While the earlier HP-80 financial calculator was also equipped with a shift key, it was not fully implemented, as most keys on the HP-80 do not have a shifted function. Other than the aforementioned improvements, the hardware of the HP-45 is nearly identical to that of the HP-35 and HP-80, sharing a common architecture, display technology and case construction.

Perhaps the most commonly noted feature of the HP-45 is its undocumented timer mode. Pressing [RCL], then pressing [CHS] [7] [8] simultaneously will activate a timer function, displaying hours, minutes, seconds and milliseconds. After entering timer mode, [CHS] starts and stops the timer. Pressing [1] through [9] while the timer is running stores the current timer value in the corresponding register, and recalls the time from the same register if the timer is stopped. Pressing [.] exits timer mode while keeping the currently displayed timer value in the bottom level of the stack, and pressing [ENTER] exits timer mode and clears the timer value. Although the HP-45 has the completely functional timer microcode, there is no external crystal to provide accuracy. The timer function is fully implemented and documented in the key-programmable HP-55.

The HP-45 also marks the last time HP would manufacture a calculator with a black case for over 30 years. Upon first seeing the HP-45, Bill Hewlett commented that black was a "very unimaginative color," and asked if all future models were going to be black as well. This singular comment resulted in all subsequent HP calculators being made in a wide range of aesthetically questionable, business-friendly colors, such as dark green, dark brown and tan. HP would not manufacture another black calculator until long after the dismantlement of their original calculator division.

HP-80 Owner's Handbook (PDF)
HP-80 Quick Reference Guide (PDF)
HP-80 Application Notes 1-10 (PDF)
HP-80 Real Estate Applications (PDF)
HP-80 Brochure: "The Hewlett-Packard HP-80 Computer Calculator" (PDF)
HP-45 Owner's Handbook (PDF)
HP-45 Quick Reference Guide (PDF)
HP-45 Applications Book (PDF)
HP-45 Brochure: "Not only is it up to 50 times faster than this..." (PDF)
HP-45 Brochure: "The Hewlett-Packard HP-45 Advanced Scientific Pocket Calculator" (PDF)
HP-45 Brochure: "compare!" (PDF)
HP-45 Accessories Catalog (PDF)
US Patent 4001569: General Purpose Calculator Having Selective Data Storage, Data Conversion and Time-Keeping Capabilities (PDF)


Hewlett-Packard HP-45 scientific calculator, 1973 Singapore production model.


HP-45 calculator in undocumented timer mode. Although the timer displays 8:47, the actual elapsed time is exactly 10:00.


HP-45 calculator, enlargement of display in total darkness. HP's magnified LED displays are brighter and have a much higher viewing angle than comparable displays from other manufacturers.


HP-45 calculator, side view.


HP-45 calculator, view of case back. Note the sticker printed in German.


HP-45 calculator, battery compartment and power supply interconnect.


HP-45 calculator, CPU board.


A well-used and non-functional HP-80 business calculator, which met its demise at the hand of a leaking NiCd battery pack.


HP-80 calculator, CPU board. The HP-35, HP-45 and HP-80 are nearly identical, the primary difference being the capacity, content and packaging of the ROM ICs. The HP-80 uses seven single-density dies, housed in an unusual metal-and-ceramic package similar to other early HP hybrid ICs. The HP-45 is equipped with two quad-sized ROMs, each housed in a conventional cerDIP.

HP Computer & Calculator Products (1966-1976)

This article is part of the [Electronic Calculators] exhibit.

©2000-2017 The Vintage Technology Association. All rights reserved.