HD6432621 Hitachi, HD6432621 Datasheet - Page 657

• Manufacturer Part Number: HD6432621
• Description: (HD64F262x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

18.3
When the RAME bit is set to 1, accesses to addresses H'FFC000 to H'FFEFBF and H'FFFFC0 to
H'FFFFFF in the H8S/2626 and H8S/2623, to addresses H'FFD000 to H'FFEFBF and H'FFFFC0
to H'FFFFFF in the H8S/2625 and H8S/2622, and to addresses H'FFE000 to H'FFEFBF and
H'FFFFC0 to H'FFFFFF in the H8S/2624 and H8S/2621, are directed to the on-chip RAM. When
the RAME bit is cleared to 0, the off-chip address space is accessed.
Since the on-chip RAM is connected to the CPU by an internal 16-bit data bus, it can be written to
and read in byte or word units. Each type of access can be performed in one state.
Even addresses use the upper 8 bits, and odd addresses use the lower 8 bits. Word data must start
at an even address.
18.4
When Using the DTC: DTC register information can be located in addresses H'FFEBC0 to
H'FFEFBF. When the DTC is used, the RAME bit must not be cleared to 0.
Reserved Areas: Addresses H'FFB000 to H'FFBFFF in the H8S/2626 and H8S/2623, H'FFB000
to H'FFCFFF in the H8S/2625 and H8S/2622, and H'FFB000 to H'FFDFFF in the H8S/2624 and
H8S/2621, are reserved areas that cannot be read or written to. When the RAME bit is cleared to
0, external address space is accessed.
Operation
Usage Notes
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