HD64F3437TF16 Datasheet, PDF (418/752 Pages) Hitachi Semiconductor – 12 V must not be applied to the S-mask model (single-power-supply specification), as this may permanently damage the device.

RAM Area Allocation in Boot Mode: In boot mode, the 96 bytes from H'FB80 to H'FBDF and
the 18 bytes from H'FF6E to H'FF7F are reserved for use by the boot program, as shown in figure
19.6. The user program is transferred into the area from H'FBE0 to H'FF6D (910 bytes). The boot
program area can be used after the transition to execution of the user program transferred into
RAM. If a stack area is needed, set it within the user program.
H'FB80
H'FBE0
Boot program
area*
(96 bytes)
User program
transfer area
(910 bytes)
H'FF6E _{Boot program}
H'FF7F ^{area* (18 bytes)}
Note: * This area cannot be used until the H8/3434F starts to execute the user program
transferred to RAM (until it has branched to H'FBE0 in RAM). Note that even after the
branch to the user program, the boot program area (H'FB80 to H'FBDF, H'FF6E to
H'FF7F) still contains the boot program.
Note also that 16 bytes (H'FB80 to H'FB8F) of this area cannot be used if an interrupt
handling routine is executed within the boot program. For details see section 19.4.9,
Interrupt Handling during Flash Memory Programming and Erasing.
Figure 19.6 RAM Areas in Boot Mode
389