This message is from the T13 list server.
On Fri, 12 Apr 2002 08:35:50 -0600, Pat LaVarre wrote: >This message is from the T13 list server. >[...] >Atap UDma cannot be quite this transparent. Atapi UDma requires >the sender to fabricate an extra byte whenever the byte count is >odd and licenses the receiver to discard without complaint the >last few bytes covered by the last Crc of the data of a command. Please Pat... We have said this many times... On the ATA/ATAPI interface... #1 If the data transfer command sends data to the device then the sender will have prepared the correct number of bytes to send to the device based on the contents of the SCSI CDB sent to the device. The sender can not, without the risk of a hang or data corruption, send less bytes or more bytes. #2 If the data transfer command receives data from the device then the receiver needs to count the bytes received. This is because the device might decide to send fewer bytes than expected based on the SCSI CDB. If a device sends more data than expected based on the SCSI CDB then the device is broken (and the receiver should be prepared to detect and report this as an error). There is NO ATA/ATAPI PROBLEM here. If there is a problem it is inside those incorrectly designed X-to-ATAPI bridge devices. *** Hale Landis *** www.ata-atapi.com ***
