Register Descriptions; Bus Control Register (Bcr) - Hitachi SH7032 Hardware Manual

8.2

Register Descriptions

8.2.1

Bus Control Register (BCR)

The bus control register (BCR) is a 16-bit read/write register that selects the functions of areas and
status of bus cycles. It is initialized to H'0000 by a power-on reset, but is not initialized by a
manual reset or in standby mode.
Bit:
Bit name: DRAME
Initial value:
R/W:
Bit:
Bit name:
Initial value:
R/W:
• Bit 15 (DRAM Enable Bit (DRAME)): DRAME selects whether area 1 is used as an external
memory space or DRAM space. 0 sets it as external memory space and 1 sets it as DRAM
space. The setting of the DRAM area control register is valid only when this bit is set to 1.
Bit 15: DRAME
0
1
• Bit 14 (Multiplexed I/O Enable Bit (IOE)): IOE selects whether area 6 is used as external
memory space or an address/data multiplexed I/O area. 0 sets it as external memory space and
1 sets it as address/data multiplexed I/O space. With address/data multiplexed I/O space, the
address and data are multiplexed and input/output is from AD15–AD0.
Bit 14: IOE
0
1
15 14 13
IOE WARP
0 0
R/W R/W R/W
7 6
— — —
0 0
— — —
Description
Area 1 is external memory space
Area 1 is DRAM space
Description
Area 6 is external memory space
Area 6 is an address/data multiplexed I/O area
12 11
RDDTY BAS
0 0 0
R/W R/W
5 4 3
— —
0 0 0
— —
10 9 8
— — —
0 0 0
— — —
2 1 0
— — —
0 0 0
— — —
(Initial value)
(Initial value)
107