HP-65
Encyclopedia
The HP-65 was the first magnetic card-programmable handheld calculator. Introduced by Hewlett-Packard
in 1974 at an MSRP
of $795, it featured nine storage registers and room for 100 keystroke instructions. It also included a magnetic card reader/writer to save and load programs. Like all Hewlett-Packard calculators of the era and most since, the HP-65 used reverse Polish notation
(RPN) and a four-level automatic operand stack
.
Bill Hewlett's design requirement was that the calculator should fit in his shirt pocket. That is one reason for the tapered depth of the calculator. The magnetic program cards fed in at the thick end of the calculator under the LED display. The documentation for the programs in the calculator is very complete, including algorithms for hundreds of applications, including the solutions of differential equations, stock price estimation, statistics, and so forth.
Functions included square root, inverse, trigonometric (sine, cosine, tangent and their inverses), exponentiation, logarithms and factorial. The HP-65 was one of the first calculators to include a base conversion function, although it only supported octal (base 8) conversion. It could also perform conversions between degrees/minutes/seconds and decimal degree values, as well as polar/cartesian coordinate conversion.
A program could be saved to mylar-based magnetically coated cards (71 mm × 9.5 mm), which were fed through the reader by a small electric motor through a worm gear and rubber roller at a speed of 6 cm/s. The recording area used only half of the width of the card. While reversing the card to store a second program was possible, it was officially discouraged (unlike in later models such as the HP-67) because the other half of the card was touched by the rubber wheel during transport, causing extra abrasion. When inserted into an extra slot between the display and the keyboard, the printing on top of the card would correspond to the top row of keys (A - E), which served as shortcuts to the corresponding program entry points.
Cards could be write-protected by diagonally clipping the top left corner of the card. HP also sold a number of program collections for scientific and engineering applications on sets of pre-recorded (and write-protected) cards.
The HP-65 had a "feature" whereby storage register R9 was corrupted whenever the user (or program) executed trigonometric functions or performed comparison tests; this kind of issue was common in many early calculators, caused by a lack of memory due to cost, power, and/or size considerations. Since the problem was documented in the manual, it is not strictly speaking a bug
.
, the HP-65 became the first programmable handheld calculator in outer space
. It was carried as a backup in case of a problem with the Apollo Guidance Computer
, although during that mission the computer did not malfunction.
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
in 1974 at an MSRP
Suggested retail price
The manufacturer's suggested retail price , list price or recommended retail price of a product is the price which the manufacturer recommends that the retailer sell the product. The intention was to help to standardise prices among locations...
of $795, it featured nine storage registers and room for 100 keystroke instructions. It also included a magnetic card reader/writer to save and load programs. Like all Hewlett-Packard calculators of the era and most since, the HP-65 used reverse Polish notation
Reverse Polish notation
Reverse Polish notation is a mathematical notation wherein every operator follows all of its operands, in contrast to Polish notation, which puts the operator in the prefix position. It is also known as Postfix notation and is parenthesis-free as long as operator arities are fixed...
(RPN) and a four-level automatic operand stack
Stack (data structure)
In computer science, a stack is a last in, first out abstract data type and linear data structure. A stack can have any abstract data type as an element, but is characterized by only three fundamental operations: push, pop and stack top. The push operation adds a new item to the top of the stack,...
.
Bill Hewlett's design requirement was that the calculator should fit in his shirt pocket. That is one reason for the tapered depth of the calculator. The magnetic program cards fed in at the thick end of the calculator under the LED display. The documentation for the programs in the calculator is very complete, including algorithms for hundreds of applications, including the solutions of differential equations, stock price estimation, statistics, and so forth.
Features
The HP-65 introduced the "tall", trapezoid-shaped keys that would become iconic for many generations of HP calculators. Each of the keys had up to 4 functions. In addition to the "normal function" printed on the key's face, a "gold" function printed on the case above the key and a "blue" function printed on the slanted front surface of the key were accessed by pushing the gold "f" and blue "g" prefix key, respectively. For example, "f" followed by "7" would access the sine function, "g" followed by "7" would calculate 1/x. For some mathematical functions, a gold "f -1" prefix key would access the inverse of the gold-printed functions, e.g. "f -1" followed by "7" would calculate the inverse sine (sin−1).Functions included square root, inverse, trigonometric (sine, cosine, tangent and their inverses), exponentiation, logarithms and factorial. The HP-65 was one of the first calculators to include a base conversion function, although it only supported octal (base 8) conversion. It could also perform conversions between degrees/minutes/seconds and decimal degree values, as well as polar/cartesian coordinate conversion.
Programming
The HP-65 had a program memory for up to 100 instructions of 6 bits which included subroutine calls and conditional branching based on comparison of x and y registers. Some but not all commands entered as multiple keystrokes were stored in a single program memory cell. When displaying a program, the key codes were shown without line numbers.A program could be saved to mylar-based magnetically coated cards (71 mm × 9.5 mm), which were fed through the reader by a small electric motor through a worm gear and rubber roller at a speed of 6 cm/s. The recording area used only half of the width of the card. While reversing the card to store a second program was possible, it was officially discouraged (unlike in later models such as the HP-67) because the other half of the card was touched by the rubber wheel during transport, causing extra abrasion. When inserted into an extra slot between the display and the keyboard, the printing on top of the card would correspond to the top row of keys (A - E), which served as shortcuts to the corresponding program entry points.
Cards could be write-protected by diagonally clipping the top left corner of the card. HP also sold a number of program collections for scientific and engineering applications on sets of pre-recorded (and write-protected) cards.
The HP-65 had a "feature" whereby storage register R9 was corrupted whenever the user (or program) executed trigonometric functions or performed comparison tests; this kind of issue was common in many early calculators, caused by a lack of memory due to cost, power, and/or size considerations. Since the problem was documented in the manual, it is not strictly speaking a bug
Software bug
A software bug is the common term used to describe an error, flaw, mistake, failure, or fault in a computer program or system that produces an incorrect or unexpected result, or causes it to behave in unintended ways. Most bugs arise from mistakes and errors made by people in either a program's...
.
Significant applications
During the 1975 Apollo-Soyuz Test ProjectApollo-Soyuz Test Project
-Backup crew:-Crew notes:Jack Swigert had originally been assigned as the command module pilot for the ASTP prime crew, but prior to the official announcement he was removed as punishment for his involvement in the Apollo 15 postage stamp scandal.-Soyuz crew:...
, the HP-65 became the first programmable handheld calculator in outer space
Outer space
Outer space is the void that exists between celestial bodies, including the Earth. It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos....
. It was carried as a backup in case of a problem with the Apollo Guidance Computer
Apollo Guidance Computer
The Apollo Guidance Computer provided onboard computation and control for guidance, navigation, and control of the Command Module and Lunar Module spacecraft of the Apollo program...
, although during that mission the computer did not malfunction.
External links
- The HP-65 at an unofficial Hewlett-Packard museum (MyCalcDB); includes a photograph of the magnetic card.
- 1975 HP Calculator Christmas Guide
- HP's Virtual Museum: HP-65
- HP-65 page at the unofficial Museum of HP Calculators