Abstract: An apparatus including a plurality of first base circuits, a plurality of second base circuits, a first test circuit, a second test circuit, and a test path. The plurality of first base circuits may be coupled to the plurality of second base circuits via one or more base circuit paths on a layout. The first test circuit may be disposed in a first distal location of the layout. The second test circuit may be disposed in a second distal location of the layout. The test path may be configured to (i) couple the first test circuit to the second test circuit and (ii) generate a test time delay from the first test circuit to the second test circuit incrementally longer than a maximum time delay generated by any of the base circuit paths.

Abstract: A slave device on a data bus has a register that stores a non-queued split master vector containing bits identifying whether a transaction with corresponding master devices have been split. An input gate is responsive to the status of the slave device and to receipt of a command from a master device when the slave device status is busy to set a bit in the non-queued split master vector identifying that the transaction with the corresponding master device is split. An output gate is responsive to a not busy status of the slave device to output the non-queued split master vector to the arbiter to re-arbitrate use of the data bus among the previously-split non-queued master devices.

Abstract: Ownership of a peripheral bus between a peripheral device and a plurality of master devices is assigned to one of the master devices. Each master device has an associated controller for controlling the peripheral device via the peripheral bus. Communication occurs without impediment between the master device and its controller that have ownership of the bus, thereby conducting transactions via the peripheral bus and peripheral device. Communication with the master device and controller not having ownership is blocked, making the controller look busy to the master device and making the master device look idle to the controller. The ownership is assigned to the master/controller pairs using an arbiter arrangement.

Abstract: A four-phase arbitration system employs a master and a slave arbiter. The master arbiter operates to provide ownership of a bus to a first device if a second device, coupled to the slave arbiter is not conducting a transaction. If the second device desires use of the bus, the slave arbiter sends a request to the master arbiter, which asserts an acknowledge signal for as long as the first device has ownership of the bus, and at least as long as a timeout of the first device. The master arbiter de-asserts its acknowledge signal when the first device ceases ownership of the bus. The slave arbiter is responsive to the de-assertion of the acknowledge signal to assert bus ownership to the second device. When the second device transaction is completed, its request signal is de-asserted to the master arbiter, causing the master arbiter to re-assert the acknowledge signal. Failure to receive a de-asserted acknowledge signal causes the slave arbiter to move to the next state.

Abstract: An electronic bus architecture for supporting posting of read requests by multiple master devices to multiple slave devices. Sideband signals added to the underlying master bus architecture permit slave devices to receive posted read requests from one or more master devices. The sideband signals are used by the slave devices and associated arbitration logic to enable the slave devices with varying latencies to return requested data to the originating masters when the data becomes available. The sideband slave bus architecture may be applied to enhance performance of AMBA based bus architectures as well as other well-known bus architectures supporting one or more master devices.

Abstract: A four-phase arbitration system employs a master and a slave arbiter. The master arbiter operates to provide ownership of a bus to a first device if a second device, coupled to the slave arbiter is not conducting a transaction. If the second device desires use of the bus, the slave arbiter sends a request to the master arbiter, which asserts an acknowledge signal for as long as the first device has ownership of the bus, and at least as long as a timeout of the first device. The master arbiter de-asserts its acknowledge signal when the first device ceases ownership of the bus. The slave arbiter is responsive to the de-assertion of the acknowledge signal to assert bus ownership to the second device. When the second device transaction is completed, its request signal is de-asserted to the master arbiter, causing the master arbiter to re-assert the acknowledge signal. Failure to receive a de-asserted acknowledge signal causes the slave arbiter to move to the next state.

Abstract: Ownership of a peripheral bus between a peripheral device and a plurality of master devices is assigned to one of the master devices. Each master device has an associated controller for controlling the peripheral device via the peripheral bus. Communication occurs without impediment between the master device and its controller that have ownership of the bus, thereby conducting transactions via the peripheral bus and peripheral device. Communication with the master device and controller not having ownership is blocked, making the controller look busy to the master device and making the master device look idle to the controller. The ownership is assigned to the master/controller pairs using an arbiter arrangement.

Abstract: A slave device includes a queue that receives commands or data from a master device for execution on a first-in, first-out basis. A status register is responsive to the queue to provide a STATUS_FULL signal when the queue is full of commands and a STATUS_EMPTY signal when the queue is empty. A configuration register provides a DEBUG signal identifying a maintenance status of the slave device. A bus control provides a QUEUE_FULL signal in response to either (1) the STATUS_FULL signal or (2) the DEBUG signal and not the STATUS_EMPTY signal to split further commands or stall the data bus.

Abstract: A slave device on a data bus has a register that stores a non-queued split master vector containing bits identifying whether a transaction with corresponding master devices have been split. An input gate is responsive to the status of the slave device and to receipt of a command from a master device when the slave device status is busy to set a bit in the non-queued split master vector identifying that the transaction with the corresponding master device is split. An output gate is responsive to a not busy status of the slave device to output the non-queued split master vector to the arbiter to re-arbitrate use of the data bus among the previously-split non-queued master devices.

Abstract: A slave device includes a queue that receives commands or data from a master device for execution on a first-in, first-out basis. A status register is responsive to the queue to provide a STATUS_FULL signal when the queue is full of commands and a STATUS_EMPTY signal when the queue is empty. A configuration register provides a DEBUG signal identifying a maintenance status of the slave device. A bus control provides a QUEUE_FULL signal in response to either (1) the STATUS_FULL signal or (2) the DEBUG signal and not the STATUS_EMPTY signal to split further commands or stall the data bus.

Abstract: A digital logic circuit, such as a FIFO memory, includes pointers, or indicators, generated in two clock domains, between which information is transferred, to indicate a location in the digital logic circuit for transferring the information into or out of the digital logic circuit within either clock domain. Each pointer is encoded with a “2-hot” encoded value within one of the clock domains. The 2-hot encoded value of each pointer is sent to the other clock domain to synchronize the pointer to the other clock domain as well as to its original clock domain. Within each clock domain, the pointer generated therein and the pointer received from the other clock domain are used to determine whether the information can be transferred into or out of the digital logic circuit.

Abstract: A digital logic circuit, such as a FIFO memory includes pointers, or indicators, generated in two clock domains, between which information is transferred, to indicate a location in the digital logic circuit for transferring the information into or out of the digital logic circuit within either clock domain. Each pointer is encoded with a “2-hot” encoded value within one of the clock domains. The 2-hot encoded value of each pointer is sent to the other clock domain to synchronize the pointer to the other clock domain as well as to its original clock domain. Within each clock domain, the pointer generated therein and the pointer received from the other clock domain are used to determine whether the information can be transferred into or out of the digital logic circuit.

Abstract: A graphics accelerator chip which interprets instructions and data transferred from a microprocessor via an external data bus logically coupled to the microprocessor. A host logic interface buffers the information received from the microprocessor with an on-chip first-in first-out (FIFO) memory which has an address space mapped onto a contiguous sequential address space of the microprocessor. A state machine having a temporary memory receives and interprets instructions and data from the FIFO memory, and routes them to a graphics register set which performs logical graphics operations based upon the graphics instructions and data. The temporary memory stores the last primitive command received, allowing the chip to perform multiple graphics operations where a primitive command is received from the microprocessor only once. A separate data bus from the host logic interface to the graphics register set enables direct access to the graphics registers from the microprocessor.