ARM VERSION 1.2 - Manual (Page 23)

Writing ARM and Thumb Assembly Language
ARM DUI 0068B Copyright © 2000, 2001 ARM Limited. All rights reserved. 2-11
Single register load and store instructions
These instructions load or store the value of a single low register from or to memory. In
Thumb state they can only access registers r0 to r7.
Multiple register load and store instructions
LDM and STM load from memory and store to memory any subset of the registers in the
range r0 to r7.
PUSH and POP instructions implement a full descending stack using the stack pointer (r13)
as the base. In addition to transferring r0 to r7, PUSH can store the link register and POP
can load the program counter.