CENTRAL PROCESSING UNIT (CPU)
2.4 Memory assignment
2.4 Memory assignment
This section describes the memory assignment in the internal area.
2.4.1 Memory assignment in internal area
SFR (Special Function Register), internal RAM, and internal ROM are assigned to the internal area. Figure
2.4.1 shows the memory assignment in the internal area.
(1) SFR area
The registers used to set the internal peripheral devices are assigned to addresses 0
16
to FF
16
. This
area is called SFR. Figures 2.4.2 and 2.4.3 show the SFR area’s memory assignment.
For each register in the SFR area, refer to each functional description in this manual.
For the state of the SFR area immediately after reset, refer to section
“3.3 State of internal area.”
(2) Internal RAM area
The internal RAM area is used as a stack area, as well as an area to store data. Accordingly, be
sure to set the nesting depth of a subroutine and multiple interrupts’ level not to destroy the necessary
data.
When the internal RAM area is followed by an unused area, do not assign a program to the last 8
bytes of the internal RAM area. (Data is allowed to be assigned there. Also, when the internal RAM
area is followed by the internal ROM area succeedingly, a program is allowed to be assigned there.)
(3) Internal ROM area
Addresses FFB4
16
to FFFF
16
are the vector addresses for reset and interrupts. (This is called the
interrupt vector table.)
Do not assign a program to the last 8 bytes of the internal ROM area. (Data is allowed to be assigned
there.)
7906 Group User’s Manual Rev.2.0
2-15
RENESAS [ RENESAS TECHNOLOGY CORP ]
