DiskOnChip 2000 DIP
4
Designing with the DiskOnChip 2000 Flash Disk
4.1 Hardware
DiskOnChip 2000 should be connected as a standard memory device, using standard memory
interface signals. Typically, DiskOnChip 2000 can be mapped to any free 8KB memory space. In PC
architectures, if the memory window allocated to DiskOnChip 2000 is larger than 8KB, an automatic
anti-aliasing mechanism prevents the firmware from being loaded more than once. Figure 1
illustrates a typical interface between DiskOnChip 2000 and a system.
OE#
CE#
D[7:0]
WE#
DiskOnChip 2000
Any Capacity
A[12:0]
Figure 2: Simplified I/O Diagram
4.2 Software
DiskOnChip 2000, under control of TrueFFS, is accessed using standard file system calls like any
other block device. Applications can write to and read from any sector on DiskOnChip 2000, which
is compatible with all diagnostic utilities, applications and file systems.
The flash memory within DiskOnChip 2000 is accessed by TrueFFS through an 8KB window in the
CPU’s memory space. TrueFFS handles the paging of this window in the flash array, as well as
providing flash disk emulation that includes flash table management, wear leveling, mapping out bad
blocks, and background space reclamation of unused flash blocks.
The same 8KB address space will be retained in future versions of DiskOnChip 2000 that offer
greater capacities.
4.3 Designing DiskOnChip 2000 into PC Architecture
When used in PC-compatible architectures, DiskOnChip 2000 is allocated an 8KB memory window
in the BIOS expansion memory range, which is usually located between 0C8000h and 0EFFFFh.
Figure 3 illustrates the DiskOnChip 2000 memory window in relation to the PC memory map.
91-SR-002-42-8L Rev.
3.4
9
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