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IDE Solid State Disk
Feature
Operation
96h
NOP - Accepted for backward compatibility.
97h
Accepted for backward compatibility. Use of this Feature is not recommended.
9Ah
Set the host current source capability. Allows tradeoff between current drawn and
read/write speed.
AAh
Enable Read Look Ahead.
BBh
4 bytes of data apply on Read/Write Long commands.
CCh
Enable Power on Reset (POR) establishment of defaults at Soft Reset.
Features 01h and 81h are used to enable and clear 8 bit data transfer modes in True IDE Mode. If the 01h feature
command is issued all data transfers shall occur on the low order D[7:0] data bus and the -IOIS16 signal shall not be
asserted for data register accesses. The host shall not enable this feature for DMA transfers.
Features 02h and 82h allow the host to enable or disable write cache in devices that implement write cache. When the
subcommand disable write cache is issued, the device shall initiate the sequence to flush cache to non-volatile
memory before command completion.
Feature 03h allows the host to select the PIO or Multiword DMA transfer mode by specifying a value in the Sector
Count register. The upper 5 bits define the type of transfer and the low order 3 bits encode the mode value. One PIO
mode shall be selected at all times. For Cards which support DMA, one Multiword DMA mode shall be selected at all
times. The host may change the selected modes by the Set Features command.
PIO default mode
PIO default mode, disable IORDY
PIO flow control transfer mode
Reserved
Multiword DMA mode
Ultra DMA Mode
Reserved
If a device supports PIO modes greater than 0 and receives a Set Features command with a Set Transfer Mode
parameter and a Sector Count register value of "00000000b", it shall set its default PIO mode. If the value is
"00000001b" and the device supports disabling of IORDY, then the device shall set its default PIO mode and disable
IORDY. A device shall support all PIO modes below the highest mode supported, e.g., if PIO mode 1 is supported PIO
mode 0 shall be supported.
Support of IORDY is mandatory when PIO mode 3 or above is the current mode of operation.
A device reporting support for Multiword DMA modes shall support all Multiword DMA modes below the highest mode
supported. For example, if Multiword DMA mode 2 support is reported, then modes 1 and 0 shall also be supported.
A device reporting support for Ultra DMA modes shall support all Ultra DMA modes below the highest mode supported.
For example, if Ultra DMA mode 2 support is reported then modes 1 and 0 shall also be supported.
If an Ultra DMA mode is enabled any previously enabled Multiword DMA mode shall be disabled by the device. If a
Multiword DMA mode is enabled any previously enabled Ultra DMA mode shall be disabled by the device. Feature 05h
allows the host to enable Advanced Power Management. To enable Advanced Power Management, the host writes the
Sector Count register with the desired advanced power management level and then executes a Set Features
command with subcommand code 05h. The power management level is a scale from the lowest power consumption
setting of 01h to the maximum performance level of FEh. Table8: Advanced power management levels show these
values.
Maximum performance
Intermediate power management levels without
Standby
Minimum power consumption without Standby
Intermediate power management levels with
Standby
Rev. A.6
Table 7: Transfer mode values
Mode
Table 8: Advanced power management levels
Level
Bits (7:3)
00000b
00000b
00001b
00010b
00100b
01000b
10000b
Mode = transfer mode number
23/32
Bits (2:0)
000b
001b
Mode
N/A
Mode
Mode
N/A
Sector Count Value
FEh
81h-FDh
80h
02h-7Fh
Nov. 2008
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