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G-H jumpers are installed.
The Drive Type Code indicates the characteristics of the drive,
defined as:
Bit 0-1
=
C3
Must be 0
Bit 2
=
0
Soft-sectored
=
1
Hard-sectored
Bit
3
=
0
Removable Media Drive
=
1
Fixed Media Drive
Bit 4-7
=
0
Must be 0
The Sector Count equals the number of sectors on a track.
Note
that for hard-sectored drives this must equal the number of
sectors set by the drive manufacturer.
6.15
BIT
BYTE
6
5
4
3
2
1
o
01
Logical Unit Number
Reserved (0)
IExtent
02
Reservation Identification
03
(MSB)
Extent List Length
94
Extent List Length
(LSB)
05
Reserved (0)
I Flag
I
Link
Figure 6-27.
RESERVE Command
The Cylinder Count is the number of data cylinders on the drive.
The ACB-5500 does not use alternate cylinders for defect
'management, so these may be included as data cylinders.
The
minimum number of cylinders is one;
the maximum is 4094.
The Data Head Count is the number of usable data surfaces. The
minimum is Ii maximum is 16.
A drive with 9 or more heads will
use the Reduced Write Current line as the high order head select.
The Reduced Write Current cylinder is the cylinder number beyond
which the controller will assert the Reduced Write Current line.
The minimum value is 0.
Note that the reduced write current line
is used as a fourth select line for drives with more than 8
heads.
The Write Precompensation cylinder is the cylinder beyond which
the controller will compensate for inner track bit shift.
The
minimum value is0.
500504-00
6-35
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