Rev.6.00 Oct.28.2004 page 561
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REJ09B0138-0600H
Section 18 RAM
18.1
Overview
The H8S/2357, H8S/2352, H8S/2398, and H8S/2392 have 8 kbytes of on-chip high-speed static RAM. The H8S/2394 has
32 kbytes of on-chip high-speed static RAM. The H8S/2390 has 4 kbytes of on-chip high-speed static RAM. The on-chip
RAM is connected to the CPU by a 16-bit bus, and accessing both byte data and word data can be performed in a single
state. Thus, high-speed transfer of word data is possible.
The on-chip RAM can be enabled or disabled by means of the RAM enable bit (RAME) in the system control register
(SYSCR).
18.1.1
Block Diagram
Figure 18-1 shows a block diagram of the 8-kbytes of on-chip RAM.
Internal data bus (upper 8 bits)
Internal data bus (lower 8 bits)
H'FFDC00
H'FFDC02
H'FFDC04
H'FFFBFE
H'FFDC01
H'FFDC03
H'FFDC05
H'FFFBFF
Figure 18-1 Block Diagram of RAM (8 kbyte)
18.1.2
Register Configuration
The on-chip RAM is controlled by SYSCR. Table 18-1 shows the address and initial value of SYSCR.
Table 18-1 RAM Register
Name
Abbreviation
R/W
Initial Value
Address
*
System control register
SYSCR
R/W
H'01
H'FF39
Note:
*
Lower 16 bits of the address.
Содержание ZTAT H8S/2357F
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