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C141-E045-02EN 6 - 7
6.2.2 Logical address
(1) CHS mode
Logical address assignment starts from physical cylinder (PC) 0, physical head (PH) 0, and
physical sector (PS) 1 and is assigned by calculating the number of sectors per track which is
specified by the INITIALIZE DEVICE PARAMETERS command. The head address is
advanced at the subsequent sector from the last sector of the current physical head address.
The first physical sector of the subsequent physical sector is the consecutive logical sector
from the last sector of the current physical sector.
Figure 6.5 shows an example (assuming there is no track skew).
127126
6462 6332
LS1
LS
63
LH4LH2LH1LH0
LS1
1
Physical sector
Physical head 0
ex: Zone 0
Physical parameter
– Physical sector: 1 to 300
Specification of INITIALIZE DEVICE PARAMETERS command
– Logical head: LH = 0 to 14
– Logical sector: LS = 1 to 63
Physical cylinder 0
300299
LS1
LS
48
LS
47
LS
63
7978
1615
LS1
LS
49
LS
63
LH6LH5LH4
1
Physical sector
LS2LS1
LS
63
Physical head 0
Physical cylinder 1
Figure 6.5 Address translation (example in CHS mode)