HD6473258CP10 Datasheet, PDF (203/301 Pages) Renesas Technology Corp – Hitachi Single-Chip Microcomputer

Section 10. RAM
10.1 Overview
The H8/3257 and H8/3256 have 2 Kbytes of on-chip static RAM, H8/325 and H8/324 have
1 Kbyte, the H8/323 has 512 bytes, and the H8/322 has 256 bytes. The on-chip RAM is connected
to the CPU by a 16-bit data bus. Both byte and word access to the on-chip RAM are performed in
two states, enabling rapid data transfer and instruction execution.
The on-chip RAM occupies the following addresses in the chip’s address space.
H8/3257, H8/3256: H'F780 to H'FF7F
H8/325, H8/324: H'FB80 to H'FF7F
H8/323: H'FD80 to H'FF7F
H8/322: H'FE80 to H'FF7F
The RAME bit in the system control register (SYSCR) can enable or disable the on-chip RAM,
permitting these addresses to be allocated to external memory instead, if so desired.
10.2 Block Diagram
Figure 10-1 is a block diagram of the on-chip RAM.
Address
H'F780
H'F782
Internal data bus (upper 8 bits)
Internal data bus (lower 8 bits)
H'F780
H'F782
H'F781
H'F783
H'FF7E
On-chip RAM
H'FF7E
H'FF7F
Even address Odd address
Figure 10-1. Block Diagram of On-Chip RAM (H8/3257)
Fig 10-1
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