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A few questions or comments for Pat... ===For ATA devices=== Do we agree that an ATA host and an ATA device both know exactly how many bytes any given command should transfer? That number is N*512 where N is 0 to 256 (for CHS and LBA28 commands)? Do we agree that an ATA host is broken if it does not expect to send or receive that number of bytes? Do we agree that an ATA device must report an error if less than N*512 bytes are sent to the host? Do we agree that an ATA device is broken if it sends more than N*512 bytes? ===For ATAPI devices=== Do we agree that by knowing the device type and the device's "block size" then the content of any given command will tell us how many bytes that command should transfer? Except for a few rare ATAPI/SCSI device that truely have variable size block sizes, do we agree that this number of bytes is exact? Do we agree that an ATAPI host is broken if it does not expect to send or receive that number of bytes? Do we agree that an ATAPI device must report an error if less than that number of bytes are sent to the host? Do we agree that an ATAPI device is broken if it sends more than that number of bytes to the host? ===More=== Do we agree that for an ATAPI Inquiry command with the Allocation length set to 5 the device will send 5 bytes plus a pad byte to the host? Do we agree that an ATAPI Read 10 for 5 blocks with a block size of 25 bytes will send 125 bytes plus a pad byte to the host? Do we agree that only the last DRQ data block or last DMA data burst will have a pad byte at the end? Do we agree that media block sizes have nothing to do with DRQ data burst sizes? Do we agree that media block sizes have nothing to do with DMA data burst sizes? Do we agree that a X-to-ATA/ATAPI bridge device, in order be a correctly implemented ATA/ATAPI host, must parse all commands that pass through it or it must receive the required information from the X side host? If we do not agree please see the CD-ROM Read CD command and tell me how a bridge knows the block size of each media block read witout looking inside the Read CD CDB or receiving the block size infomation from the X side host) *** Hale Landis *** [EMAIL PROTECTED] *** *** Niwot, CO USA *** www.ata-atapi.com *** Subscribe/Unsubscribe instructions can be found at www.t13.org.
