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[ BC [EMAIL PROTECTED] ] As far as I know ... 1) SwDma and MwDma do not let data burst or stream more quickly than Pio4 does - all share the 17e+6 byte/s limit. However, Wintel motherboards by design do commonly waste a lot more cpu time streaming data in via Pio than in via SwDma or via MwDma. The (insignificant) competition is commonly less broken. However, Ata Pio, if distinguished from Atapi Pio, then has no protocol for reporting an error after copying the last block in, whereas Ata SwDma and Ata SwDma do. 2) The standard of x200 (512) bytes/block is more de facto than de jure. Scsi devices, including the Scsi over Ide that is Atapi, vary in how they report block size. Devices whose op x12 Inquiry data byte 0 says they are of type x00 DirectAccess, x05 CdRom, x0E DirectAccessBastardisation (aka RBC), share the quality of reporting via op x25 Read Capacity what their block size is, whenever the block size in question is reasonably small and the media in question contains less than xFFFF:FFFF Lba's (2TiB @ 0.5KiB/block). 3) Scsi over Ide, unlike Scsi over Usb and Scsi over 1394 and ..., omits to pass over the bus the "specific field(s) that explicitly define - (a) if the command contains data and if it does then (b) What is the length of the data associate to the packet command?". Whether that omission is consequential or not has been the subject of extensive, largely fruitless debate here since last November (2001). The whitepaper giving my perspective is: http://members.aol.com/plscsi/cdbcomplete.html Pat LaVarre -----Original Message----- From: Yaniv Shapira [mailto:[EMAIL PROTECTED]] Sent: Sun 4/28/2002 10:23 AM To: [EMAIL PROTECTED] Cc: Subject: [t13] ATAPI Questions This message is from the T13 list server. Dear T13, Can you help with the following questions: - Which ATA/ATAPI devices (if at all) being used today requires multiword DMA protocol? - The ATA protocol defines a sector size of 512 bytes. Right? What is the sector size used by ATAPI devices? - Looking at the 12/16 bytes packet command can I find a specific field(s) that explicitly define - (a) if the command contains data and if it does then (b) What is the length of the data associate to the packet command? Thanks, Yaniv Shapira Product Definition Group Galileo - Marvell Company Email - [EMAIL PROTECTED] Tel - 972 8 9247555 ext. 398 FAX - 972 8 9247554
