SCS I Description
M axtor Atlas 10K III 5-175
The W RIT E LON G and READ LONG c om mands allow the initiator to issue raw
reads a nd writ es of phys ical sec to rs addres sed as log ical blocks with an a ssumed sec tor
length of 512 bytes. These commands are used to verify the correction capability of
the drive's ECC and to create defects of a known kind and location to verify the drive's
recovery a nd bad sector handling policies. The data format and field descriptions are
sh o w n in T able 5-220 and T ab l e 5-221 resp e c ti v e ly.
WRITE LO NG Com mand Descriptor Block- D a ta Form at
WR IT E LON G Command-F ield Descriptions
0 Opera tion C ode (3 Fh )
1 Reserved RelAdr
2 - 5 Logical Block Address
6 Reserved
7 - 8 By te Transfer Length (562)
9 Control
RelAdr Rel ativ e Address. This drive does not suppo rt this fea ture; the field must
be 0.
Logical Block
Address The address of the first logical sector where the Write operation will occur.
Byte Transfer
Length
Must be 562. This value re fl ects the number of bytes spann ed by the ECC,
including the ECC itself, rounded up to the next word (this is easiest un-
derstood in bits: 4096 data bits + 1 force erro r bit + 15 Logical Block Ad-
dress bits + 16 cross chec k bits + 2 pad bits + 360 ECC bits + 6 pad
bits that are not wri tten to m edia but are only needed f or transfer = 4496
bits or 562 bytes). Any other value in this field results in a CHECK CON-
DITION status and the appropriate sense data.
The initiator should first issue a READ LONG, then modify the data portion
only, and then issue a WRITE LONG. It is also recommended that the drive
be reformatted after these com m ands are used.