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1.6.4
Voltage Sense Signal -VS1
The Voltage Sense Signal -VS1, pin 43, of the
SDP3B FlashDisk is grounded because the Card
Information Structure (CIS) can be read at 3.3
volts. In the SDP5A FlashDisk, this pin is not
grounded because the SDP5A FlashDisk CIS can
only be read at 5 volts.
Note:
In some early platforms, the -VS1 pin (pin 43) is
also the Refresh pin for DRAM cards. Plugging
the SDP3B into a platform supporting the
Refresh pin will hang the bus.
1.6.5
True IDE Mode
The SDP3B FlashDisk differs from the SDP5A
FlashDisk in that it can be configured in True IDE
Mode. See section 4.6 True IDE Mode I/O Transfer
Function.
1.6.6
Identify Drive Information
Word 51 of the
Identify
information has a default value of 0000H for the
SDP5A
FlashDisk.
information for this word is "PIO data transfer
cycle timing mode 0."
For the SDP3B FlashDisk, word 51 of the Identify
Drive Command information has a default value
of 0001H. The data field type information for this
word is "PIO data transfer cycle timing mode 1."
1.7
Functional Description
SDP3B
FlashDisks
intelligent subsystem as shown in the block
diagram,
Figure
(microprocessor)
subsystem
capabilities not found in other types of memory
cards. These capabilities include:
1. Standard ATA register and command set
(same as found on most magnetic disk
drives).
2. Host independence from details of erasing
and programming flash memory.
3. Sophisticated system for managing
defects (analogous to systems found in
magnetic disk drives).
SanDisk SDP3B FlashDisk Product Manual © 1998 SANDISK CORPORATION
Drive
Command
The
data
field
type
contain
a
high
level,
1-1.
This
intelligent
provides
many
SDP3B FlashDisk Product Manual
4.
Sophisticated system for error recovery
including a powerful error correction code
(ECC).
5.
Power management for low power
operation.
1.7.1
Flash Technology Independence
The 512 byte sector size of SDP3B FlashDisk 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 SDP3B FlashDisk. 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 SDP3B FlashDisk 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 SDP3B FlashDisk 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
SDP3B FlashDisks 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. For
instance, disk drives do not typically perform a
read after write to confirm the data is written
correctly because of the performance penalty that
would be incurred. SDP3B FlashDisks do a read
after write under margin conditions to verify that
the data is written correctly (except in the case of
a Write without Erase Command). In the rare case
that a bit is found to be defective, SDP3B
FlashDisks replace this bad bit with a spare bit
within the sector header. If necessary, SDP3B
FlashDisks will even replace the entire sector
with
a
spare
sector.
transparent to the host and does not consume any
user data space.
This
is
completely
11
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