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CHAPTER 5 CPU ARCHITECTURE
5.1.2 Internal data memory space
The
µ
PD78078 and 78078Y Subseries units incorporate the following RAMs.
(1) Internal high-speed RAM
This is a 1024 x 8-bit configuration in the area FB00H to FEFFH 4 banks of general registers, each bank
consisting of eight 8-bit registers, are allocated in the 32-byte area FEE0H to FEFFH.
The internal high-speed RAM can also be used as a stack memory.
(2) Internal buffer RAM
Internal buffer RAM is allocated to the 32-byte area from FAC0H to FADFH. Internal buffer RAM is used
for storing transmit/receive data of serial interface channel 1 (3-wire serial I/O mode with automatic transmit/
receive function). When not used in the 3-wire serial I/O mode with automatic transmit/receive function,
internal buffer RAM can also be used as normal RAM.
(3) Internal expansion RAM
Internal expansion RAM is allocated to the 1024-byte area from F400H to F7FFH.
5.1.3 Special function register (SFR) area
An on-chip peripheral hardware special function register (SFR) is allocated in the area FF00H to FFFFH. (Refer
to Table 5-3. Special Function Register List of 5.2.3 Special function register (SFR)).
Caution Do not access addresses where the SFR is not assigned.
5.1.4 External memory space
The external memory space is accessible by setting the memory expansion mode register (MM). External memory
space can store program, table data, etc. and allocate peripheral devices.