Section 4 Caches; Overview; Features; Table 4.1 Cache Features (Sh7751) - Hitachi SH7751 Hardware Manual

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
Capacity
Type
Line size
Entries
Write method

Section 4 Caches

Instruction Cache
8-kbyte cache
Direct mapping
32 bytes
256 entry
Operand Cache
16-kbyte cache or 8-kbyte cache +
8-kbyte RAM
Direct mapping
32 bytes
512 entry
Copy-back/write-through selectable
Rev. 3.0, 04/02, page 87 of 1064