SH7020 Datasheet, PDF (115/509 Pages) Renesas Technology Corp – SuperH™ RISC engine

• On-chip ROM space in area 0: Always 32 bits
• External memory space in area 0: 8 bits when MD0 pin is 0, 16 bits when the pin is 1
• On-chip peripheral module space in area 5: 8 bits when the A8 address bit is 0, 16 bits when it
is 1
• Area 6: If A27 = 0, area 6 is 8 bits when the A14 address bit is 0, 16 bits when A14 is 1
• On-chip RAM space in area 7: Always 32 bits
See table 8.6 in section 8.3, Address Space Subdivision, for more information on how the space is
divided.
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 by the standby mode.
Bit: 15
14
13
12
11
10
9
8
Bit name: DRAME IOE WARP RDDTY BAS
—
—
—
Initial value: 0
0
0
0
0
0
0
0
R/W: R/W R/W R/W R/W R/W
—
—
—
Bit: 7
6
5
4
3
2
1
0
Bit name: —
—
—
—
—
—
—
—
Initial value: 0
0
0
0
0
0
0
0
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 for external memory space and 1 sets it for 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
Description
Area 1 is external memory space (initial value)
Area 1 is a DRAM space
• 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 for external memory space and
1 sets it for address/data multiplexed I/O space. With address/data multiplexed I/O space,
address and data are multiplexed and input/output is from AD15–AD0.
RENESAS 97