The HP 20b Business Consultant is a financial calculator published in 2008 by Hewlett-Packard. Its function is similar to HP 10bII and includes scientific and statistical functions.
Hardware specification
The HP 20b uses a 2 lines display with the first line an 8 character scrolling display and 11 indicators and the second line for 12+3 digit display. It also uses 2 CR2032 batteries, an AtmelAT91SAM7L128 30 MHz processor. The processor's serial interface is accessible from under the battery cover to allow the firmware to be updated using a special cable from HP.
Functions
The HP 20b contains functions similar to the HP 10bII, with financial functions including: TVM, IRR, NPV, NUS, amortization, depreciation, bonds, yield and accrued interest, interest conversion, list-based cashflow analysis, cashflows, break-even analysis.
Math/Statistics functions include: list-base, 1 and 2 variable statistics, mean, standard deviation, population deviation, standard error, forecasting, correlations and covariance, +, -, ×, ÷, %, 1/x, +/-, scientific notation, n!, combinations, permutations, rounding, random numbers, LOG, LN, 10×, PL, square root, trigonometry, probability. For input modes, it supports RPN, Chain and Algebraic input. It also included several added features include: date calculation, display format and language preferences, memory functions, editing, scroll keys.
Criticism
Many users claim that they dislike the model because it lacks the feedback when pressing the keys, and the menus make things complicated.
Along with the HP 30b, the HP 20b calculator is particularly conducive to repurposing, since both the hardware and software are made public by HP. Several projects have been started around reusing this calculator for other purposes. The most advanced is the WP 34S, a programmable scientific calculator that combines the functionality of the HP-42S and HP-16C and includes many other novel features and functions. A firmware branch with a complex number lock mode is called WP 34C. The WP 31S is a stripped-down non-programmable version of the WP 34S, designed to be easier to use.