This message is from the T13 list server.
On Sun, 14 Apr 2002 09:10:27 -0600, Pat LaVarre wrote: >This message is from the T13 list server. >"Residual byte length is the number of bytes not transferred to, >or received from, the target SCSI device. >And the examples: >"For example, if the ASPI buffer length for a SCSI Inquiry >command is set for 100 bytes, but the target only returns back 36 >bytes, this makes for a residual length of 64 bytes. >"Another example, if the ASPI buffer length for a SCSI write >command is set for 514 bytes, but the target only takes 512 >bytes, this makes for a residual length of 2 bytes. Pat, please, here we are talking about how the host side hardware or software handles the possible difference between the size of the application I/O buffer in memory and the amount of data that a device transfers on the I/O interface. The concept of the host side hardware or software reporting this value has been with us since the 1950's. Unfortunately, the PCI bus ATA host adapters designers at Intel apparently don't understand the need to report this value. That still does not make this a T13 problem, unless you want the T13 "host adapter standard" to address it? This is not a T13 PIO or DMA data transfer problem. An ATA or ATAPI device will attempt to transfer the amount of data as specified by the current command. The interface works only because a device transfers that amount of data (or less for read commands) or the device signals an error on the command. I can clearly see now that you are confusing the actions of host side software and hardware with how you think ATA/ATAPI PIO and DMA work. Host software or hardware that rounds data transfers up or down to some byte/word/dword boundary is not a T13 I/O interface problem. *** Hale Landis *** www.ata-atapi.com ***
