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Command
Seek Forward
Upper (SFU)
Tag 02
Seek Forward
Lower (SFL)
Tag 03
83318200 E
TABLE 3-3.
COMMANDS
Definition/Function
1.
An
output information tag.
2. Loads Upper 2 bits of seek difference information (512,256) into
temporary storage for gating into the Difference Counter during
a subsequent Seek Forward Lower (Tag 03).
The data is received
via the bidirectional data lines.
3. This tag must precede the Seek Forward Lower Command.
4. Bidirectional data lines are decoded as follows:
Decode
DIFF 256
DIFF 512 (BR3C9 only)
Not Used
1.
An
output information tag.
2. Loads lower 8 bits of seek difference information (tracks to go)
from bidirectional data lines into the Difference counter.
3. This tag must be preceded by a Seek Forward Upper (Tag 03) or the
fault line is raised along with Bit 24 of the Detailed Status
Byte.
4. This command causes the drive to seek forward the number of cyl-
inders indicated by the difference count.
5. The Bidirectional data lines decode as follows:
ill
Decode
~
Decode
2 0
DIFF 1
24
DIFF 16
21
DIFF 2
2 5
DIFF 32
22
DIFF 4
2 6
DIFF 64
2 3
DIFF 8
27
DIFF 128
3-26.1
I
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