SH7708 Datasheet, PDF (211/633 Pages) Renesas Technology Corp – SuperH™ RISC engine

10.1.5 Area Overview
Space Allocation: The SH7708 Series architecture provides for a 32-bit virtual address space. The
virtual space is divided into five areas by the value of the upper bits of the address. The physical
space is divided into eight areas with a 29-bit address space.
Virtual space can be allocated at will to physical spaces using a memory management unit
(MMU). For details, refer to section 3, Memory Management Unit, which describes area
allocation for physical spaces.
As shown in table 10.4, the SH7708 Series can be connected directly to seven areas of memory/PC
card, and it outputs chip select signals (CS0–CS6, CE2A, CE2B) for each of them. CS0 is asserted
during area 0 access; CS6 is asserted during area 6 access. When DRAM, synchronous DRAM, or
pseudo-SRAM is connected to area 2 or 3, signals such as RAS, CAS, RD/WR, and DQM are also
asserted. When PCMCIA interface is selected in area 5 or 6, in addition to CS5/CS6, CE2A/CE2B
are asserted for the corresponding bytes accessed.
For virtual address spaces P0 and P3, when the memory management unit (MMU) is on, any
physical address can be generated by the MMU for a virtual address. Consequently, figure 10.2
can be applied when the MMU is off, and when the MMU is on and the physical addresses
corresponding to virtual addresses are identical except for the top 3 bits. When virtual addresses
are translated to arbitrary physical addresses, refer to table 10.3, Physical Address Space Map.
H'00000000
,,,, _H'20000000
H'40000000
,,,, _H'60000000
,,,, _H'80000000
,,,, H'A0000000
H'C0000000
,,,,,,,, _H'E0000000
P0, U0
P1
P2
P3
P4
Area 0 (CS0)
H'00000000
Area 1 (CS1)
H'04000000
Area 2 (CS2)
H'08000000
,,,,,,Area 3 (CS3)
Area 4 (CS4)
Area 5 (CS5)
Area 6 (CS6)
Reserved area
H'0C000000
H'10000000
H'14000000
H'18000000
Physical address space
Virtual address space
Figure 10.2 Correspondence between Virtual Address Space and Physical Address Space
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