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3.1.2 Internal data memory space
The µ PD780208 Subseries units incorporate the following RAMs.
(1) Internal high-speed RAM
Internal high-speed RAM is allocated to the 1024-byte area from FB00H to FEFFH of the µ PD780208 Subseries.
Four banks of general-purpose registers, each bank consisting of eight 8-bit registers are allocated in the 32-
byte area FEE0H to FEFFH.
This area cannot be used as a program area in which instructions are written and executed.
The internal high-speed RAM can also be used as a stack memory.
(2) Internal expansion RAM
Internal expansion RAM is allocated to the 1024-byte area from F400H to F7FFH of the µ PD780206, 780208,
and 78P0208.
This area can also be used as a normal data area similar to the internal high-speed RAM, as well as a program
area in which instructions can be written and executed.
The internal expansion RAM cannot be used as a stack memory.
(3) Buffer RAM
Buffer RAM is allocated to the 64-byte area from FAC0H to FAFFH. 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, buffer RAM can be used
as normal RAM.
(4) VFD display RAM
VFD display RAM is allocated to the 80-byte area from FA30H to FA7FH. VFD display RAM can also be used
as normal RAM.
3.1.3 Special-function register (SFR) area
On-chip peripheral hardware special-function registers (SFRs) are allocated to the area FF00H to FFFFH (see
Table 3-3 Special-Function Register List under 3.2.3 Special-function registers (SFRs)).
Caution Do not access addresses where SFRs are not assigned.
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CHAPTER 3 CPU ARCHITECTURE
User's Manual U11302EJ4V0UM
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