defined varables currently active in the calculator, and you can use the arrow keys if there are more
than will fit on one screen.
You can also use STO+, STO–, STO× and STO÷ even in this case since the types of the things you
are operating are the same.
We can deal with the four registers of the stack as we deal with the memory positions. In this case the
lines of the stack are called ST X, ST Y, ST Z and ST T respectively. To access this we press '.'
before the name of the register. For example: 5 STO . ST X puts 5 in line x of the stack. The
submenu that is displayed when we press '.' Actually has two other items, ST L and IND. ST L refers
to the LASTx register, and IND is used for indirect parameters.
As the content of the stack can change easily I don't think "STO ." is a good thing. But I cannot say
the same of "RCL ." which may be very useful to get the content especially of registers z and t. You
can also use STO and RCL with +, -, x and ÷ and '.' to work with the content of the registers of the
stack. For example:5 STO ÷
We can use an indirect parameter by pressing . IND when using STO or RCL or any other
calculator function that happens to allow indirect parameters. With indirect addressing, we specify a
location where the actual parameter is stored, rather than the parameter itself. That location could be
a named variable, one of the numbered storage registers, or a stack register. For example, to assign
the value 125 to the register specified in the variable ABC:
10 STO "ABC"
125 STO . IND "ABC"
menu has the following submenus:
FCN PGM REAL CPX MAT MEM
FCN: It shows all the functions available in HP-42S calculator. It has many lines and one must use the
▼ and ▲ to navigate through the lines. Here you are going to find important functions we
don't see in the keyboard including hyperbolic functions (SINH, COSH, etc), functions to
work with integer and real numbers like IP (integer part) and FP (fraction part), programming
functions, etc. Don't forget you can also use XEQ "function name".
PGM: It shows all variables with programs in the memory.
REAL: It shows all variables with real numbers in the memory. (But does not show numbers in the
numbered registers R
CPX: It shows all variables with complex numbers.
MAT: It shows all variables with matrices. The REGS matrix always appears. It contains the numeric
MEM: It shows all available memory.
3.2 More on the
We already saw some of the CLEAR menu functions, but there are also:
ST Z divides register z by 5.
sets variable ABC to the value 10
stores 125 in the register pointed to indirectly by "ABC"
returns the value 125 to the x-register