53
Chapter 3 CPU Function
3
3.3 NOTES
(1)
A program fetch from the internal RAM area is prohibited.
(2) Operation of the stack pointer
In stack addressing, the entire 64K bytes can be accessed. No stack area can be mapped into the SFR area
or internal ROM area.
(3) Special function register (SFR)
Never access an address to which no SFR is mapped in the area from 0FF00H to 0FFFFH. If this is attempted,
the
µ
PD78214 may enter a deadlock. To clear the deadlock, a reset signal must be input to the device.
(4) Initializing the stack pointer
The SP becomes undefined when RESET is input. Meanwhile, nonmaskable interrupts can be acknowledged
immediately after a reset is released. If a nonmaskable interrupt request occurs while the SP is undefined
immediately after a reset is released, an unpredictable operation may be carried out. To minimize this danger,
initialize the SP immediately after a reset is released. For details, see
Section 12.3.2
.
Содержание PD78212
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