HP Voyager series

The HP Voyager Series is a series of landscape format RPN calculators produced by Hewlett Packard. The series includes the HP 10C, HP 11C, HP 12C, HP 15C, and HP 16C.

Design

A unique aspect of the Voyager series is the landscape layout of the calculator. Combined with the small physical size of the calculator, this permitted a 10 digit display calculator to fit inside an average shirt pocket (the original design goal of the HP35) without undue stress on the latter.

In an attempt at standardizing the product lineup, HP designed all the Voyagers around the same chasis, which was a two-piece plastic design, secured using four screws hidden under the rubber feets. The front plate housed the keyboard legend, the display acryllic window and the faceplate which had an indent for a HP logo and name plaque. These were all secured using glue. The rear plate held a glued-on painted metallic plate with additional information, the battery compartment holding three LR/SR44 cells, as well as the rubber feets. Internally the PCB is secured to the front plate using heat-stakes, with up to three surface mount ICs soldered to the backside. The LCD display is held by eight bent metallic feet to the PCB, and is electrically connected to the front side of the PCB via elastomeric connector (otherwise known as ZEBRA connectors).

The display is a 10-digit 7-segments LCD display with an extra minus sign to the left, featuring annunciators for * low battery, USER mode, f/g shifts, BEGIN, (G)RAD, C(omplex), D.MY and PRGM mode. Not all are used on any given calculator. It can display 10 digits fixed point number, or 8 digits of mantissa and 2 exponents for positive exponents, and one less mantissa for negative exponents. When displaying the full mantissa, the sign and decimal points are discarded. There are no provisions for adjusting the display contrast.

One significant design change was the vertical and horizontal rearranging of the four function keys, breaking from the tradition established by HP35 in 1972. Due to the great commercial success of the Voyagers, this new arrangement was subsequently inherited by later Pioneers and beyond, a decision that to this day remains highly controversial within the HP community.

HP41C and all before "Classic HP layout":
- 1 2 3
+ 4 5 6
x 7 8 9
/ 0 .(?)
Voyagers and beyond:
1 2 3 /
4 5 6 x
7 8 9 -
0 .(?)+

Some complaints were that this arrangement broke long-standing user habit, broke the physical proximity of the operators to the stack lifting ENTER key, or that the new location is illogical as the most used arithmetic operators tends to be the multiply and addition keys, which should be grouped together, etc., Others defended that this arrangement allowed easier single-handed operation for right-handed users using their dominant hand, which was arguably more important for the Voyager form factor. Internally values are stored as 10 digits BCD with 2 digit mantissa, for a total of 4 digit (56 bytes). Flag 9 is set when the value overflows causing the display to blink, the offending value is replaced with 9.99... E99 in the stack.

(-1)^S M.MMMMMMMMM XS XX
M: mantissa, 10 digits
S: sign, 0 = +; 9 = -
XS: exponent sign, 0 = +; 9 = -
XX: exponent, 2 digits

XS = 0: exponent is interpreted as XX
XS = 9: exponent is interpreted as XX-100

Since ROM space was less of a constraint by that time, HP starting from the HP-91 implemented more nuianced algorithm for certain classes of operations to make them exact, for example with small integers raised to small integer exponents, and special trigonometry values. Accuracy is thus rather nuianced: the Voyagers did not employ persistent guard digits, meaning that what the user see is what is actually stored in the calculator. Internally the Voyagers calculates with 13 digits intermediary results, but immediately rounds them off to 10 digits upon finishing. Built in functions are guaranteed to have at worse the wrong 9th digit, and usually to no more than 1 off by the last digit. (On the HP 15C, for complex operations the accuracy is specified with regard to the complex value formed by real and imaginary parts, which means that each individual component can have error as large as the fourth significant digit.)

Models

A general summary of the Voyager series is given as follows:

Calculators of the Voyager Family

	Model	Introduction	Discontinuation
Scientific	HP 10C	2nd Sept. 1982	Before March 1984
	HP 11C	1st of Spet. 1981	End of 1988
	HP 15C	1st of July 1982	End of 1988
Business	HP 12C	1st Sept. 1981	Variant still in production
Computer	HP 16C	July 1982	Circa 1989

Both the HP 10C and HP 16C (despite the latter being rather sought after today) found little success in the market, while the HP 11C's successes have been largely eclipsed by the more successful HP 15C, which has became highly sought after in the years following its discontinuation. The most successful HP 12C in various form is still in production.

Hardware revisions

Pre-1996 datecode format (YYWW)

Datecode	Model	CPU	Additional info
2137	HP 11C	1LE3

See also

• HP Pioneer series