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Chapter 2 CPU Basics
Bank Function
Table 2-6-1 Address Range
2-6 Bank Function
2-6-1 Overview
CPU of MN101C00 series has basically 64 KB memory address space. On this LSI, address space can be
expanded up to 4 banks (256 KB) based on units of 64 KB, by bank function.
2-6-2 Bank Setting
Bank function can be used by setting the proper bank area to the bank register for source address
(SBNKR) or the bank register for destination address (DBNKR). At reset, both of the SBNKR register
and the DBNKR register indicate bank 0. Bank function is valid after setting any value except "00" to the
SBNKR register or the DBNKR register.
When the both registers of SBNKR and DBNKR are operated at interrupt processing, pushing onto the
stack or popping are necessary.
When bank area is changed at interrupt processing, pushing onto the stack or popping must
be done by program, if it necessary.
The stack area should be set in the area of bank 0, always. Furnished C compiler does not
support bank function.
During bank function is valid, I/O short instruction should be used for access to the special
function register area (x'03F00' to x'03FFF'). For access to the memory space x'13F00' to
x'13FFF', x'23F00' to x'23FFF' and x'33F00' to x'33FFF', both instructions of register indirect
and register relative indirect should be used. [
Chapter 2 2-1-8. Addressing Modes]
SBA1 SBA0
(DBA1) (DBA0)
0 0 Bank 0 x'00000' to x'0FFFF'
0 1 Bank 1 x'10000' to x'1FFFF'
1 0 Bank 2 x'20000' to x'2FFFF'
1 1 Bank 3 x'30000' to x'3FFFF'
Bank area Address range