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5.6.10 Read Buffer - E4h
The Read Buffer command enables the host to read the current contents of the CompactFlash Storage Card's
sector buffer. This command has the same protocol as the Read Sector(s) command.
Bit ->
Command (7)
C/D/H (6)
Cyl High (5)
Cyl Low (4)
Sec Num (3)
Sec Cnt (2)
Feature (1)
5.6.11 Read DMA – C8h
This command uses DMA mode to read from 1 to 256 sectors as specified in the Sector Count register. A sector
count of 0 requests 256 sectors. The transfer begins at the sector specified in the Sector Number Register. When this
command is issued the CompactFlash Storage Card sets BSY, puts all or part of the sector of data in the buffer. The Card
is then permitted, although not required, to set DRQ, clear BSY. The Card asserts DMAREQ while data is available to be
transferred. The Card asserts DMAREQ while data is available to be transferred. The host then reads the (512 *
sector-count) bytes of data from the Card using DMA. While DMAREQ is asserted by the Card, the Host asserts -DMACK
while it is ready to transfer data by DMA and asserts -IORD once for each 16 bit word to be transferred to the Host.
Interrupts are not generated on every sector, but upon completion of the transfer of the entire number of sectors to be
transferred or upon the occurrence of an unrecoverable error.
At command completion, the Command Block Registers contain the cylinder, head and sector number of the last
sector read. If an error occurs, the read terminates at the sector where the error occurred. The Command Block Registers
contain the cylinder, head, and sector number of the sector where the error occurred. The amount of data transferred is
indeterminate.
When a Read DMA command is received by the Card and 8 bit transfer mode has been enabled by the Set Features
command, the Card shall return the Aborted error.
Transcend Information Inc.
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Drive
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59
80X CompactFlash Card
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V 1 . 1
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