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Register: 0x49
SCSI Timer One (STIME1)
Read/Write
7
6
R
HTHBA
x
0
R
Reserved
HTHBA
Handshake-to-Handshake Timer Bus Activity
Enable
Setting this bit causes this timer to begin testing for SCSI
REQ/, ACK/ activity as soon as SBSY/ is asserted,
regardless of the agents participating in the transfer.
GENSF
General Purpose Timer Scale Factor
Setting this bit causes this timer to shift by a factor of 16.
Refer to the
description for details.
HTHSF
Handshake-to-Handshake Timer Scale Factor
Setting this bit causes this timer to shift by a factor of 16.
Refer to the
description for details.
GEN[3:0]
General Purpose Timer Period
These bits select the period of the general purpose timer.
The time measured is the time between enabling and
disabling of the timer. When this timing is exceeded, the
GEN bit in the
is set. Refer to the table under
(STIME0), bits [3:0], for the available time-out periods.
Note:
To reset a timer before it expires and obtain repeatable
delays, the time value must be written to zero first, and then
written back to the desired value. This is also required
when changing from one time value to another.
SCSI Registers
5
4
GENSF
HTHSF
0
0
SCSI Timer Zero (STIME0)
SCSI Timer Zero (STIME0)
SCSI Interrupt Status One (SIST1)
3
GEN[3:0]
0
0
0
register
register
SCSI Timer Zero
0
0
7
6
5
4
[3:0]
register
4-87
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