Seagate STT8000A - Manual (Page 68)

Chapter 5 ATAPI Interface
Page 60 STT8000A Product Manual
Write command
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation code (0Ah)
1 Reserved 1 (Fixed)
1 Reserved
2 (MSB)
3 Transfer Length
4 (LSB)
5 Reserved
The Transfer Length specifies the number of fixed 512 byte blocks to be transferred.
A transfer length of 0 indicates that no data is to be transferred but is used on some
drives to put DSC into write buffer mode.
The DSC bit is reset (0) after this command is accepted and all data has been
transferred. This bit is set (1) when there are at least 52 empty blocks in the buffer
available for the next WRITE command. Issuing a WRITE command when the DSC
bit is reset (0) will keep the ATA bus busy (BSY=1) until buffer