Toshiba T2N - Manual (Page 149)

1. Overview
136 PROSEC T2N
The memory which can be used by user is called user memory. The
user memory can be divided by configuration into main memory
and peripheral memory. And the user memory can be devided by
function into user program memory and user data memory.
The main memory is a built-in RAM memory with battery backed
up. On the other hand, the peripheral memory is a memory
configured by EEPROM. The peripheral memory can be used as
back up for main memory (user program and register data) .
The user program memory has a capacity of 24K steps (step is a
unit for instruction storage), and stores the user program configured
by a series of instructions.
The user data memory stores variable data for user program
execution. It is separated by function into input/output registers,
data registers, etc.