Abstract: A method for back-off retry with priority routing includes routing a data transfer between an input of a single, cohesive SAS expander and an output of the SAS expander via at least one inter-expander link (IEL), the expander including a first SAS expander and at least one additional SAS expander. The method includes routing a first OPEN request on a direct path through the first SAS expander to a port of a device and routing a second OPEN request on an alternate path from the first SAS expander and through a second SAS expander to the port of the device. The method further includes, upon determination of a failed link or a busy link, re-routing the data transfer from the second SAS expander to the first SAS expander or a third SAS expander, or retrying the data transfer through the second SAS expander.

Abstract: A method for back-off retry with priority routing in a single, cohesive SAS expander includes routing a data transfer between an input of a single, cohesive SAS expander and an output of the single, cohesive SAS expander, wherein the single, cohesive expander includes a first SAS expander, and at least one additional SAS expander via at least one inter-expander link (IEL). The routing of data may further include routing a first OPEN request on a direct path through the first SAS expander to a port of a device and routing a second OPEN request on an alternate path from the first SAS expander and through a second SAS expander to the port of the device. The method further includes determining link availability between the second SAS expander and the port of the device, and, upon determination of a failed link or a busy link, re-routing the data transfer from the second SAS expander to the first SAS expander or a third SAS expander, or retrying the data transfer through the second SAS expander.

Abstract: A method for back-off retry with priority routing in a single, cohesive SAS expander includes routing a data transfer between an input of a single, cohesive SAS expander and an output of the single, cohesive SAS expander, wherein the single, cohesive expander includes a first SAS expander, and at least one additional SAS expander via at least one inter-expander link (IEL). The routing of data may further include routing a first OPEN request on a direct path through the first SAS expander to a port of a device and routing a second OPEN request on an alternate path from the first SAS expander and through a second SAS expander to the port of the device. The method further includes determining link availability between the second SAS expander and the port of the device, and, upon determination of a failed link or a busy link, re-routing the data transfer from the second SAS expander to the first SAS expander or a third SAS expander, or retrying the data transfer through the second SAS expander.

Abstract: A state machine may have a sequence that is called by multiple threads within the state machine. Prior to calling the sequence, an address specific to the current state is stored in an address register. After the sequence has executed, the address register is queried and the thread may continue. Many different threads may call the sequence. In more complex hardware implemented state machines, the total number of gates may be reduced significantly.

Abstract: A state machine may have a sequence that is called by multiple threads within the state machine. Prior to calling the sequence, an address specific to the current state is stored in an address register. After the sequence has executed, the address register is queried and the thread may continue. Many different threads may call the sequence. In more complex hardware implemented state machines, the total number of gates may be reduced significantly.

Abstract: A bus interface and a receiver in the bus interface receive signals from a computer bus, such as a SCSI (Small Computer System Interface) bus, and deskew and synchronize the signals into valid data and control signals. The signals are aligned and then a portion of the signals is offset to ensure that the other signals have sufficient time to stabilize before being latched. The alignment is performed by adding and subtracting delay units to and from the signals. The offset is determined by a self-calibration logic that uses the same type of delay units.