Long Read
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Long Read
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SCSI devices generally support a "long read" command, op code &28. This is an extension to the usual 6-byte read command &8 which takes 3 bytes for the sector address and just one byte for the number of sectors in operation. The long read is a 10-byte command taking 4 bytes for the sector address and 2 bytes for the number of sectors, allowing much larger devices to be addressed and a much greater range of sectors to be operated on in each call. Long read isn't documented for the Domesday VP415, but if you click on the picture links above, you will learn more than the manual will tell you.