HP 15c - Manual (Page 90)

90
Section 8
Program Branching
and Controls
Although the instructions in a program are normally executed sequentially,
it is often desirable to transfer execution to a part of the program other than
the next line. Branching in the HP-15C may be simple, or it may depend on
a certain condition. By branching to a previous line, it is possible to execute
part of a program more than once – a process called looping.
The Mechanics
Branching
The Go To (t) Instruction. Simple branching – that is, unconditional
branching – is carried out with the instruction t label. In a running
program, t will transfer execution to the next appropriately labeled
program or routine (not to a line number).
The calculator searches forward in memory, wrapping around through line
000 if necessary, and resumes execution at the first line containing the
proper label.
Looping. If a t instruction specifies a label at a lower-numbered line
(that is, a prior line), the series of instructions between the t and the
label will be executed repeatedly – possibly indefinitely. The continuation