3 MEMORY MAP
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
3-3
Area 0 (IRAM, Cache Memory)
3.2
IRAM
3.2.1
Area 0 includes a 12K-byte IRAM (internal RAM) that can be used as a general-purpose RAM to store data and
execute instructions. It is located at addresses 0x0 to 0x2fff.
In addition to the 12K-byte IRAM, the 20K-byte IVRAM (internal VRAM), which is located in Area 3 by default,
can be relocated to Area 0 to use it as a general-purpose RAM. Write 0 to IVRAM_LOC/MISC_IRAM_LOC regis-
ter when using IVRAM as an additional IRAM. (See the “Misc Registers (MISC)” chapter for more information on
the register.)
In most cases, the CPU accesses IRAM (excluding IVRAM relocated to Area 0) in one cycle regardless of access
data size. While the IVRAM (relocated to Area 0) access cycle can be configured as one or two cycles according to
the COREWT/MISC_RAMWT register setting. (See the “Misc Registers (MISC)” chapter for more information on
the register.)
Note: The address range from 0x0 to 0xff (256 bytes) in IRAM is reserved for use as the debugging
RAM area. Be sure to avoid accessing this area from the user program and the debugger. When
using a debugger, specify 0x80 as the debugging RAM address.
c33 das 0x60000 0x80
Cache Memory
3.2.2
Area 0 also includes two 1K-byte RAMs, one of them is located at addresses 0x1f800 to 0x1fbff and can be used as
an instruction cache, and another is located at addresses 0x1fc00 to 0x1ffff and can be used as a data cache. Each
1K-byte RAM is enabled as a cache memory by setting the cache controller. For more information on the caches,
see the “Cache Controller (CCU)” chapter.
Areas 1 and 2 (Reserved for System)
3.3
Areas 1 and 2 are reserved for the system. Be sure to avoid accessing these areas from the user program and the de-
bugger.
Area 3 (IVRAM, DSTRAM)
3.4
IVRAM
3.4.1
Area 3 includes a 20K-byte IVRAM (internal VRAM) for the LCD controller and graphics engine. It is located at
addresses 0x90000 to 0x94fff.
The 20K-byte IVRAM can be relocated to Area 0 to use it as a general-purpose RAM by writing 0 to IVRAM_
LOC/MISC_IRAM_LOC register. IVRAM_LOC must be set to 1 (default) when using IVRAM. (See the “Misc
Registers (MISC)” chapter for more information on the register.)
IVRAM located in Area 3 is accessed in four or five cycles, according to the BUSWT/MISC_RAMWT register set-
ting.
DSTRAM
3.4.2
Area 3 includes a 512-byte RAM (DSTRAM) located at addresses 0x80000 to 0x801ff.
DSTRAM is used to store the control table for the DMA controller. It can also be used as a general-purpose RAM.
When using the color look-up table function for the LCDC, DSTRAM is configured as the look-up table memory
(LUTRAM) by setting DSTRAM_CFG/MISC_IRAM_LOC register and LUTPASS/LCDC_DISPMOD register. In
this case, DSTRAM cannot be accessed from the CPU and DMAC. For more information on the look-up table and
memory switching, see the “LCD Controller (LCDC)” chapter.
Note: When DSTRAM is switched to LUTRAM, locate the DMAC control table in IVRAM (Area 3) or an
external RAM.