HD6417021 Hitachi Semiconductor, HD6417021 Datasheet - Page 441

• Manufacturer Part Number: HD6417021
• Description: SuperH RISC engine
• Manufacturer: Hitachi Semiconductor

17.1
The SH7020 and SH7021 has 1-kbytes of on-chip RAM. The on-chip RAM is linked to the CPU
and direct memory access controller (DMAC) with a 32-bit data bus (figure 17.1). The CPU can
access data in the on-chip RAM in byte, word, or long word units. The DMAC can access byte or
word data. On-chip RAM data can always be accessed in one state, making the RAM ideal for use
as a program area, stack area, or data area, which require high-speed access. The contents of the
on-chip RAM are held in both the sleep and standby modes. Memory area 7 addresses H'FFFFC00
to H'FFFFFFF are allocated to the on-chip RAM.
17.2
Accesses to addresses H'FFFFC00–H'FFFFFFF are directed to the on-chip RAM. Memory area 7
(H'F000000–H'FFFFFFF) is divided into shadows in 1 kbyte units. All shadow accesses are on-
chip RAM accesses. For more information on shadows, see section 8, Bus State Controller.
Overview
Operation
H'FFFFFFC
H'FFFFC00
H'FFFFC04
Figure 17.1 Block Diagram of RAM
Section 17 RAM
H'FFFFFFD
H'FFFFC01
H'FFFFC05
Internal data bus (32 bits)
On-chip RAM
H'FFFFC02
H'FFFFC06
H'FFFFFFE
H'FFFFC03
H'FFFFC07
H'FFFFFF
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