HP-15C Quick Reference
Approx. 462 bytes of memory corresponding to 66 registers, 7 bytes each,
4-level stack, Last-X, index register I.
Nonvolatile memory, mostly merged program commands (1 byte per
Displayed when the contents of the nonvolatile (continuous memory) has
Turn off, press & hold ON, press ".", release ON, release "."
This toggles between using a dot or comma for the decimal separator.
Turn off, press & hold ON, press "-", release ON, release "-"
This clears all permanent memory!
Displays memory assignment in the form "RR UU pp – n" with:
RR: Number of highest storage register. At least 1 which means that R0, R1
and the index register I are always present. Register 0-19 correspond to
0-9 & .0-.9 and can be accessed directly by STO/RCL. Higher registers
can be reached thru indirect addressing only.
UU: Number of uncommitted registers. Use DIM to commit them to storage
registers. Uncommitted registers are automatically converted to
program space when needed.
pp: Number of registers containing program instructions. One register
consists of 7 bytes and can hold 7 program steps (except for a few
instructions that occupy two bytes).
Number of bytes left before next uncommitted register is converted to
In total there are 66 registers corresponding to 462 bytes.
The initial setup is "19 46 0-0": 20 storage registers (0-19), 46 uncommitted
registers, corresponding to approx. 322 program steps.
Use this command to select the number of registers committed to storage.
The argument must be passed in X. It specifies the highest storage register
Registers containing program instructions cannot be converted to storage
X must be at least 1 so there will always be R0 and R1 available.
The maximum is 65
Select fix-point format
Select scientific format with exponent
Select engineering format with exponent always being a multiple of 3
Memory & Display