Application Notes; Notes On Data Access To Empty Areas - Hitachi H8/3664 Hardware Manual

Reset state
Reset
occurs
Program halt state
2.9

Application Notes

2.9.1

Notes on Data Access to Empty Areas

The address space of the H8/3664 Series CPU includes empty areas in addition to the RAM,
registers, and ROM areas available to the user. If these empty areas are mistakenly accessed by an
application program, the following results will occur.
• Data transfer from CPU to empty area
The transferred data will be lost. This action may also cause the CPU to misoperate.
• Data transfer from empty area to CPU
Unpredictable data is transferred.
42
Reset cleared
Reset occurs
Reset
occurs
SLEEP instruction executed
Figure 2.14 State Transitions
Exception-handling state
Interrupt
source
Interrupt
source
Program execution state
Exception-
handling
complete