HP 12C Platinum Owner's Handbook Manual page 90

92 Section 8: Programming Basics
program memory consists of 8 program lines, and there are 20 storage registers
available for storage of data.
rogram Memory
As you key in a 310th instruction, storage register R
into seven new lines of program memory. The instruction you key in is stored in
program line 310, and the instruction i000 is automatically stored in
program lines 311 through 316.
rogram Memory
310
3 1 1
312
313
314
315
316
Program memory is automatically expanded like this whenever another seven
instructions have been keyed into program memory – that is, when you key an
instruction into program line 317, 324, 331 etc. In each case, the additional
program lines made available are converted, seven lines at a time, from the last
available data storage register (whether or not data has been stored in that
register; if it has, it will be lost). Furthermore, the six new program lines
(following the 317th, 324th etc.) will each contain the instruction i000.
Storage Registers
is automatically converted
0.9
Storage Registers