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CHAPTER 3 CPU ARCHITECTURE
User
’
s Manual U14701EJ3V0UD
3.1.2 Internal data memory space
The
μ
PD780318, 780328, and 780338 Subseries products incorporate the following RAM.
(1) Internal high-speed RAM
This RAM is assigned to FB00H to FEFFH (1,024 bytes).
The 32-byte area FEE0H to FEFFH is assigned to four general-purpose register banks configured of eight 8-
bit registers as one bank.
Instructions cannot be written and executed using this RAM as a program area.
The internal high-speed RAM can also be used as a stack memory.
(2) Internal expansion RAM
The area F200H to F7FFH (1,536 bytes) is assigned to the internal expansion RAM.
The internal expansion RAM can be used as a normal data area in the same way as the internal high-speed RAM.
This RAM can also be used for writing and executing instructions as a program area.
(3) LCD display RAM
The area FA00H to FA27H (40
×
8 bits) is assigned to the LCD display RAM. Among this space, the area that
can be used as LCD display data varies depending on the product, as described in Table 3-3.
LCD display RAM can also be used as normal RAM. Therefore, the area not used as LCD display data can be
used as normal RAM.
Table 3-3. Area That Can Be Used as LCD Display Data
Part Number
Area That Can Be Used as LCD Display Data
μ
PD780316, 780318
FA00H to FA17H (24 bytes)
μ
PD780326, 780328
FA00H to FA1FH (32 bytes)
μ
PD780336, 780338
FA00H to FA27H (40 bytes)
μ
PD78F0338
P80/S32 to P87/S39 and P90/S24 to P97/S31 are used as port output:
FA00H to FA17H (24 bytes)
P80/S32 to P87/S39 or P90/S24 to P97/S31 is used as port output:
FA00H to FA1FH (32 bytes)
P80/S32 to P87/S39 and P90/S24 to P97/S31 are used as segment output:
FA00H to FA27H (40 bytes)
3.1.3 Special function register (SFR) area
On-chip peripheral hardware special function registers (SFRs) are allocated in the area FF00H to FFFFH (refer
to
Table 3-4 Special Function Register List
in
3.2.3 Special function register (SFR)
).
Caution Do not access addresses where an SFR is not assigned.