49
CHAPTER 3 CPU ARCHITECTURE
Preliminary User’s Manual U16035EJ1V0UM
3.1.2 Internal data memory space
The
µ
PD780024AS, 780034AS Subseries products incorporate an internal high-speed RAM, as listed below.
Table 3-3. Internal High-Speed RAM Capacity
Part Number
Internal High-Speed RAM
µ
PD780021AS, 780031AS
512
×
8 bits (FD00H to FEFFH)
µ
PD780022AS, 780032AS
µ
PD780023AS, 780033AS
1024
×
8 bits (FB00H to FEFFH)
µ
PD780024AS, 780034AS
µ
PD78F0034BS
The 32-byte area FEE0H to FEFFH is allocated four general-purpose register banks composed of eight 8-bit
registers.
The internal high-speed RAM can also be used as a stack memory.
3.1.3 Special function register (SFR) area
An on-chip peripheral hardware special function register (SFR) is allocated in the area FF00H to FFFFH (refer to
3.2.3 Special function register (SFR) Table 3-5 Special Function Register List
).
Caution Do not access addresses where the SFR is not assigned.
3.1.4 External memory space
The external memory space is accessible with memory expansion mode register (MEM). External memory space
can store program, table data, etc., and allocate peripheral devices.