Key Mapping for Free 42s

This program is a remarkably faithful representation of the classic HP 42s calculator, one of the most flexible and powerful hand calculators ever created.

In its current (2019) incarnation, this program comes in two versions - a binary based one that takes advantage of the hardware of modern computers, and which is natively faster than the decimal version which more accurately mimics the functioning of the classic calculator. Unless you are using a program which depends upon this association, the binary version is the most efficient.

This key mapping was taken from this URL


Standard Key Mapping for the Free 42s

The table below is a listing of the default mapping for Free 42s. (I am not sure actually, how to modify this in any event.)

Function Key Map Explanation
Square Root q Square root
Square Q The square of a number
yx V , shift-F2 The ‘inverse’ of ‘inverse’
1/x v , F2 think inVerse
Sigma+ F1, a think ‘Accumulate’
Sigma- shitf-F1
LOG o, F4 log
10x O, shift-F4 10 to the xth
LN l, F5 ln (natural logarithm)
ex L, shift-F5
XEQ x, F6 think Xeq (i.e. execute)
GOTO X, shift-F6
STO m think Memory
COMPLEX M Shift m
RCL r think ‘r’ecall
% shift-R think peRcent
Rdown ‘d’ think ‘d’own
pi shift-D
sin,cos,tan s,c,t standard trig functions
asin,acos,atan S, C, T
ENTER Enter or Return
ALPHA Shift-Enter or shift-Return Enter ‘alpha’ mode
X<>Y w think s’w’ap (or s(w)ap)
Last X shift-W
+/- n think (n)egative
Modes shift-N
Exponent e exponent key
DISP shift-E enter display mode
Backspace <- key backspace key
CLEAR shift-backspace
CursorUp Up key
MATRIX ‘(‘ Enter matrix mode
STAT ‘?’ Enter stats mode
PROB Ctrl-8 Note this key combo
SOLVER ‘&’ Shift-7
BST shift CursorUp
SST shift CursorDown
CONVERT ‘%’
PGM.FCN ‘#’ Programming Functions
PRINT ‘ ‘
PROGRAM Enter programming mode
R/S ‘\’ an arbitrary key choice apparently
CATALOG =

In A..F mode (meaning the "A..F" submenu of the BASE menu), the PC keyboard keys A through F are mapped to the top row of the calculator's keyboard (Sigma+ through XEQ); these mappings override any other mappings that may be defined for A through F.

In ALPHA mode, all PC keyboard keys that normally generate printable ASCII characters, enter those characters into the ALPHA register (or to the command argument, if a command with an alphanumeric argument is being entered). These mappings override any other mappings that may be defined for those keys.