Fujitsu MBA3300 NP SERIES, Technical Manual

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38 C141-C015
1.4.5 Signal driving conditions
(1) Signal status value
Table 1.12 shows the correspondence between the input interface signal level at the receiving end
and its logic state.
Table 1.12 Signal status at receiving end
Single-ended type signal state
Logic state
Asynchronous,
Fast-5, Fast-10
Fast-20
LVD type signal
state
True, "1", or
asserted
Low (less than 0.8
VDC)
Low (less than 1.0
VDC)
Low (-3.6 to -0.030
VDC)
False, "0", negated
or released
High (more than 2.0
VDC)
High (more than 1.9
VDC)
High (0.030 to 3.6
VDC)
(2)
Signal driving method
Two driving methods are available: "OR-tied" type and "non-OR-tied" type as indicated in Table
1.13.
Table 1.13 Signal driving method
Driving method
"OR-tied" type "non-OR-tied" type
Signal status
False (*1) No SCSI device drives a signal.
The signal becomes false when
the terminating resistor circuit
is biased. A particular SCSI device drives
the signal false. Otherwise, no
SCSI device drives the signal.
True A SCSI device drives the signal true
*1 In this manual, the signal is said to be false if one of the following conditions is satisfied.
1. The signal is actually driven by a SCSI device to become false (non-OR-tied type).
2. No SCSI device is driving the signal (OR-tied type or non-OR-tied type).
If the BSY, SEL and RST signals may be driven by two or more SCSI devices simultaneously in
the interface operating sequence, they must be driven in the OR-tied method. All signals except
for SEL, BSY, RST and DB(P_CRCA, P1) are not driven by multiple SCSI devices
simultaneously. However, the DBP signals must be driven false in the ARBITRATION phase.
All signals driven in OR-tied and non-OR-tied method can be mixed on the same signal line of
SCSI bus except for BSY, SEL and RST signals.