| 摘要 |
When more than two terminators are on a SCSI bus the bus is said to be "over-terminated", and when less than two terminators are on the bus, the bus is said to be "under-terminated". When the SCSI bus is either under or over terminated, the bus does not function, and often the user does not know why the bus is not functioning. Apparatus and a method are provided for indicating to the user when the bus is not properly terminated. A terminator monitoring system and method operate in conjunction with the bus. A precision resistor is connectable to the bus so that a voltage drop is produced across the precision resistor. A circuit monitors the value of the produced voltage drop across the precision resistor to provide an indication of the number of terminators on the bus. A switch selectably connects the precision resistor to the bus, and there is a source of a reference voltage. The monitoring circuit includes a comparison circuit responsive to the voltage drop across the precision resistor and to the reference voltage for indicating whether the number of terminators on the bus exceeds a limit or is less than the limit. The system notifies a system user of an undesired (or improper) termination condition of the bus, wherein each of a plurality of devices connected to the bus may have a termination enabled.
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