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Section 4 Caches
4.1
Overview
4.1.1
Features
The SH7751 Series has an on-chip 8-kbyte instruction cache (IC) for instructions and 16-kbyte
operand cache (OC) for data. Half of the memory of the operand cache (8 kbytes) can also be used
as on-chip RAM. The features of these caches are summarized in table 4.1.
The SH7751R incorporates a 16-kbyte instruction cache (IC) for instructions and a 32-kbyte
operand cache (OC) for data. Half of the operand cache memory (16 kbytes) can also be used as
on-chip RAM. When the EMODE bit in the CCR register is cleared to 0 in the SH7751R, both the
IC and OC are set to SH7751 compatible mode. Operation is as shown in table 4.1. When the
EMODE bit in the CCR register is set to 1, the cache characteristics are as shown in table 4.2.
After a power-on reset or manual reset, the initial value of the EMODE bit is 0.
The SH7751 Series supports two 32-byte store queues (SQs) for performing high-speed writes to
external memory. SQ features are shown in table 4.3.
Table 4.1
Cache Features (SH7751)
Item
Instruction Cache
Operand Cache
Capacity
8-kbyte cache
16-kbyte cache or 8-kbyte cache +
8-kbyte RAM
Type
Direct mapping
Direct mapping
Line size
32 bytes
32 bytes
Entries
256 entry
512 entry
Write method
Copy-back/write-through selectable
Summary of Contents for SH7751
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