MD2203 ETC, MD2203 Datasheet - Page 12

• Manufacturer Part Number: MD2203
• Description: Disk Onchip 2000 DIP
• Manufacturer: ETC

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DiskOnChip 2000 appears to the system’s hardware as a standard EEPROM, via the System
Interface block. The host cycles are passed to the Flash Control block, to be written to or read from
the flash device.
To ensure the highest level of reliability, each cycle is monitored by the EDC/ECC (Error Detection
and Correction) block. In write cycles, the EDC/ECC block generates a syndrome for every sector
that contains data, which is stored in the flash together with the sector. When the sector is read, the
syndrome is regenerated for the data and compared with the original syndrome. When a mismatch is
detected, it is repaired.
The boot block is responsible for answering the BIOS expansion search in PC architectures. After the
BIOS identifies DiskOnChip 2000 as a valid BIOS expansion device, it executes the code stored in
the boot block. The BIOS then loads the TrueFFS software from the flash memory into the host
memory, delivering full disk capabilities to the operating system. This code is identical for all
DiskOnChip 2000 capacities, since TrueFFS automatically detects the memory capacity of
DiskOnChip 2000.
6.1 Error Detection and Correction (EDC/ECC)
DiskOnChip 2000 uses the Reed-Solomon EDC/ECC algorithm to ensure high data reliability. Each
time a block of data is written to the flash, a 6-byte checksum is also written. Each time the data is
read back from the flash, a new 6-byte code is computed. TrueFFS uses these checksums for error
detection and, if necessary, error correction.
91-SR-002-42-8L Rev. 3.4
Theory of Operation
A[0:12]
D[0:7]
CE#
WE#
OE#
VCC
GND
Figure 4: DiskOnChip 2000 Simplified Block Diagram
Interface
System
Boot Block
(IPL ROM)
EDC/ECC
Flash
Control
Flash
DiskOnChip 2000 DIP
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