
13
1.5
Memory Map
The SH7410 processor is a memory-mapped device with a 4-Gbyte address space, addressed with
32 bits. It can access 64 Mbytes of external memory space, divided into four 16-Mbyte areas
called CS0 to CS3.
The processor provides two on-chip memories, called X and Y memory, each mapped into the
linear address space. The two memory spaces can be accessed in parallel, so two data transfer
operations can be executed during the same processor clock cycle: one X memory access and one
Y memory access. X memory and Y memory each consist of a RAM page (4 kbytes) and a ROM
page (24 kbytes).
The purpose of X and Y memory is to provide a means for the fast execution of DSP algorithms.
The X and Y memory access operations (MOVX and MOVY) can be executed as individual
instructions, or combined with each other and up to two other parallel DSP operations to form a
single instruction. Memory spaces other than X and Y memory can be accessed only with
conventional single-operation instructions.
The addresses H'00000000 through H'000003FF map to the exception vectors (see section 4,
Exception Processing and section 5, Interrupt Controller). These exception vectors may be stored
internally or externally, depending on the memory map mode chosen.
The peripheral module registers are memory-mapped and assigned to an address in the range
H'0C000000 through H'0DFFFFFF, regardless of the memory map mode.
The SH7410 processor has two memory map modes: internal CS0 memory mode and external
CS0 memory mode. Figures 1.3 and 1.4 show the corresponding memory maps. In external CS0
memory mode, the exception vectors (including the reset vector) are stored in external memory. In
internal CS0 memory mode, the exception vectors are stored in the X ROM memory. The MD3
and MD4 signals select the memory map mode during reset. When both signals are low, internal
CS0 memory mode is selected. Otherwise, external CS0 memory mode is selected. Section 7.3,
Access Size and Data, describes the use of these external signals.
In internal CS0 memory mode (figure 1.3), the SH7410 processor uses the first 128 kbytes of
address space for its on-chip ROM and RAM memories. The exception vectors reside in the first 1
kbyte of memory space, so the reset vector resides in the on-chip X ROM. A program stored in X
ROM can start without accessing external memory. The first 16 Mbytes of memory space cannot
access external memory in this mode. The 48 Mbytes of address space from H'01000000 to
H'03FFFFFF are available for the external memory.