SMCXXXAF Datasheet, PDF (71/82 Pages) Numonyx B.V – 32 Mbyte, 64 Mbyte, 128 Mbyte, 256 Mbyte and 512 Mbyte 3.3 V / 5 V supply CompactFlash™ card

SMCxxxAF
CF-ATA command description
9.24
Write Multiple command (C5h)
This command is similar to the Write Sectors command. The card sets BSY within 400 ns of
accepting the command. Interrupts are not presented on each sector but on the transfer of a
block which contains the number of sectors defined by Set Multiple. Command execution is
identical to the Write Sectors operation except that the number of sectors defined by the Set
Multiple command is transferred without intervening interrupts.
DRQ qualification of the transfer is required only at the start of the data block, not on each
sector. The block count of sectors to be transferred without intervening interrupts is
programmed by the Set Multiple Mode command, which must be executed prior to the Write
Multiple command.
When the Write Multiple command is issued, the Sector Count register contains the number
of sectors (not the number of blocks or the block count) requested. If the number of
requested sectors is not evenly divisible by the sector/block, as many full blocks as possible
are transferred, followed by a final, partial block transfer. The partial block transfer is for n
sectors, where:
n = (sector count) module (block count).
If the Write Multiple command is attempted before the Set Multiple Mode command has
been executed or when Write Multiple commands are disabled, the Write Multiple operation
will be rejected with an aborted command error.
Errors encountered during Write Multiple commands are posted after the attempted writes
of the block or partial block transferred. The Write command ends with the sector in error,
even if it is in the middle of a block. Subsequent blocks are not transferred in the event of an
error. Interrupts are generated when DRQ is set at the beginning of each block or partial
block.
The Command Block registers contain the cylinder, head and sector number of the sector
where the error occurred and the Sector Count register contains the residual number of
sectors that need to be transferred for successful completion of the command. For example,
each block has 4 sectors, a request for 8 sectors is issued and an error occurs on the third
sector. The Sector Count register contains 6 and the address is that of the third sector.
Note: The current revision of the CompactFlash memory card only supports a block count of
1 as indicated in the Identify Drive command information. The Write Multiple command is
provided for compatibility with future products which may support a larger block count.
Table 76 defines the Write Multiple command byte sequence.
Table 76. Write Multiple
Bit
7
6
5
4
3
2
1
0
Command (7)
C5h
C/D/H (6)
1
LBA
1
Drive
Head
Cyl High (5)
Cyl Low (4)
Cylinder High
Cylinder Low
Sect Num (3)
Sector Number
Sect Cnt (2)
Sector Count
Feature (1)
X
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