US 5,671,376 A · Universal SCSI electrical interface system

Abstract

A universal electrical interface system connects to a small computer system interface (SCSI) bus. In a passive embodiment, a set of single-ended receivers and a set of differential receivers receive electrical signals on the SCSI bus according to the single-ended or differential protocol, respectively, when each set of receivers is enabled. In an active embodiment, a set of single-ended transceivers and a set of differential transceivers transmit and receive electrical signals on the SCSI bus according to the single-ended or differential protocol, respectively, when each set of transceivers is enabled. A control mechanism connected to both sets of receivers or transceivers automatically determines whether the SCSI bus is configured to use either the single-ended or differential parallel interface protocol and selectively enables the set of single ended receivers or transceivers, or the set of differential receivers or transceivers. The receivers and transceivers present an appropriate set of TTL signals to a SCSI device that have values which correspond to the proper value of the electrical signals on the SCSI bus, regardless of whether the SCSI bus is configured to use the single-ended protocol or the differential protocol. In a preferred embodiment, a single universal SCSI connector detachably connects to and receives and/or transmits electrical signals from a SCSI bus configured to use either the single-ended or differential parallel interface protocols.

Claims14

Dependent claims

A universal electrical interface connection system for connecting to and transmitting and receiving electrical signals to and from a Small Computer Systems Interface (SCSI) bus that is configured to define a set of electrical signals according to either a single-ended electrical interface protocol or a differential electrical interface protocol, the connection system comprising:

a set of single-ended transceivers for transmitting and receiving the electrical signals on the SCSI bus according to the single-ended protocol when the set of single-ended transceivers is enabled;
and
a set of differential transceivers for transmitting and receiving the electrical signals on the SCSI bus according to the differential protocol when the set of differential transceivers is enabled;
control means operably connected to the set of single-ended transceivers and the set of differential transceivers for automatically selecting the appropriate set of transceivers to be enabled depending upon whether the SCSI bus is configured to use the single-ended or the differential protocol,
wherein any electrical signals on the SCSI bus which are commonly grounded in both the single-ended and differential protocols are permanently grounded and wherein at least one of the remaining electrical signals on the SCSI bus which is grounded in only one of the single-ended and differential protocols is switchably grounded under control of the control means.

2 more elements

a set of single-ended transceivers for transmitting and receiving the electrical signals on the SCSI bus according to the single-ended protocol when the set of single-ended transceivers is enabled;
and
a set of differential transceivers for transmitting and receiving the electrical signals on the SCSI bus according to the differential protocol when the set of differential transceivers is enabled;
control means operably connected to the set of single-ended transceivers and the set of differential transceivers for automatically selecting the appropriate set of transceivers to be enabled depending upon whether the SCSI bus is configured to use the single-ended or the differential protocol, the control means including:
an enable line connected to each of the set of single-ended transceivers and to each of the set of differential transceivers;
and
a programmable processor means for setting the enable line to at least a first or a second logical state, the processor means including:
an input register connected to a selected signal from the SCSI bus from which the processor means can determine whether the SCSI bus is configured to use the single-ended protocol or the differential protocol;
and
an output register for selectively setting the enable line in response to a determination made by the processor means as to whether the SCSI bus is configured to use the single-ended protocol or the differential protocol,
such that the enable line selectively enables the set of single-ended transceivers and disables the set of differential transceivers when the enable line is in the first logical state and selectively disables the single-ended transceivers and enables the differential transceivers when the enable line is in the second logical state.

8 more elements

at least one set of transceivers for transmitting and receiving the electrical signals on the SCSI bus;
and
control means for automatically controlling the at least one set of transceivers to utilize the single-ended protocol or the differential protocol to interpret the electrical signals on the SCSI bus depending upon whether the SCSI bus is configured to use the single-ended protocol or the differential protocol, the control means including:
a control line connected to each transceiver of the at least one set of transceivers;
and
a programmable processor means for setting the control line to at least a first or a second logical state, the processor means including:
an input register connected to a selected signal from the SCSI bus from which the processor means can determine whether the SCSI bus is configured to use the single-ended protocol or the differential protocol;
and
an output register for selectively setting the control line in response to a determination made by the processor means as to whether the SCSI bus is configured to use the single-ended protocol or the differential protocol.

6 more elements

at least one set of transceivers for transmitting and receiving the electrical signals on the SCSI bus;
and
control means for automatically controlling the at least one set of transceivers to utilize the single-ended protocol or the differential protocol to interpret the electrical signals on the SCSI bus depending upon whether the SCSI bus is configured to use the single-ended protocol or the differential protocol, the control means including:
a control line connected to each transceiver of the at least one set of transceivers;
and
means for setting the control line to at least a first or a second logical state in response to a selected signal on the SCSI bus such that the control line determines whether the at least one set of transceivers utilize the single-ended protocol or the differential protocol to interpret the electrical signals on the SCSI bus,
wherein the selected signal is the DIFFSENS signal and the DIFFSENS signal is not switched to ground when the connection system is connected to a SCSI bus configured use the single-ended protocol.

4 more elements

Dependencies are inferred from the claim text.

Universal SCSI electrical interface system

Life of this patent

Universal SCSI electrical interface system

Life of this patent

Abstract

Claims14