Specifications

Identify Drive Command
Word Bit Description
20 — Buffer type*
(0000
H
= not specified
0001
H
= a single-ported single-sector buffer
which is not capable of simultaneous data
transfers to or from the host and the disc;
0002
H
= a dual ported multisector buffer
capable of simultaneous data transfers to or
from the host and the disc;
0003
H
= a dual ported multisector buffer
capable of simultaneous transfers with a read
caching capability;
0004
H
through FFFF
H
are reserved:
These codes are typically not used by the
operating system but are useful for diagnostic
programs that perform initialization routines, in
which a different interleave value may be
desirable for 0001
H
, 0002
H
or 0003
H
above.)
21 — Buffer size in 512-byte increments*
22 — Number of ECC bytes available on read/write long
commands*
(If the contents of this field are set to a value
other than 4, the Set Features command (bit
44
H
) must be used to specify the appropriate
number of ECC bytes to be transferred during
read/write long commands)
23–26 — Firmware revision*
(8 ASCII characters, left justified and padded
with spaces [20
H
])
27–46 — Model number*
(40 ASCII characters, left justified and padded
with spaces [20
H
])
47 15–8 Seagate reserved
47 7–0 00
H
= Read/write multiple commands not imple-
mented;
xx H = Maximum number of sectors that
can be transferred per interrupt on read and
write multiple commands.
continued from previous page
42 ATA Interface Reference Manual, Rev. C