Product manual

CompactFlash Memory Card Product Manual Preliminary
SanDisk CompactFlash Memory Card Product Manual Rev. 8 © 2001 SANDISK CORPORATION
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1.7.1 Flash Technology Independence
The 512 byte sector size of the CompactFlash
Memory Card is the same as that in an IDE
magnetic disk drive. To write or read a sector (or
multiple sectors), the host computer software
simply issues a Read or Write command to the
CompactFlash Memory Card. This command
contains the address and the number of sectors to
write/read. The host software then waits for the
command to complete. The host software does not
get involved in the details of how the flash
memory is erased, programmed or read. This is
extremely important as flash devices are expected
to get more and more complex in the future. Since
the CompactFlash Memory Card Series uses an
intelligent on-board controller, the host system
software will not require changing as new flash
memory evolves. In other words, systems that
support the CompactFlash Memory Card today
will be able to access future SanDisk cards built
with new flash technology without having to
update or change host software.
1.7.2 Defect and Error Management
CompactFlash Memory Cards contain a
sophisticated defect and error management
system. This system is analogous to the systems
found in magnetic disk drives and in many cases
offers enhancements. If necessary, CompactFlash
Memory Cards will reunite data from a defective
sector to a good sector. This is completely
transparent to the host and does not consume any
user data space.
The CompactFlash Memory Card soft error rate
specification is much better than the magnetic disk
drive specification. In the extremely rare case a
read error does occur, CompactFlash Memory
Cards have innovative algorithms to recover the
data.
These defect and error management systems,
coupled with the solid state construction, give
CompactFlash Memory Cards unparalleled
reliability.
1.7.3 Wear Leveling
CompactFlash Memory Card Series products do
not require or perform a Wear Level operation. The
command is supported as a NOP operation to
maintain backward compatibility with existing
software utilities.
1.7.4 Using the Erase Sector and Write without
Erase Commands
As a result of the CompactFlash Card’s high write
performance, the Erase Sector and Write Without
Erase Commands are no longer supported. There
will be no net gain in the use of these commands.
Since the write performance of SanDisk products
typically improves with the introduction of next
generation flash technologies, this feature is no
longer required. Any platforms employing these
commands in previous SanDisk products will not
be affected as a result of the elimination of this
function. The Erase Sector Command will still
erase the sectors but the Write Without Erase
Command will perform a normal Write Command
resulting in no net gain in write performance.