Abstract: The invention in its preferred embodiment involves a data producer such as a host processor that multiplexes two or more data byte streams onto a single communication link, whether serial or parallel, for transmission to a data consumer such as an ink-jet or laser printer, scanner or facsimile machine. The data are packetized with header information including a start byte, a destination channel ID byte and size byte. At the data consumer, the data under control of a state machine are header-stripped, unpacked, routed and stored in appropriate two or more ring buffers. Exception handling such as data loss or framing error recovery may be performed by the data consumer's communicating its status to the data producer or by the use of handshake lines such as READY or BUSY, rendering the invented method and apparatus compatible with unidirectional or bidirectional hardware links.

Abstract: The present invention provides a method of pacing a stream of data transmitted from a data source to a buffered data destination with a determined number of available storage units, the data destinations being configured to consume data and thereby to free storage units for receipt of additional data.

Abstract: A method for controlling packet communications between a source and destination causes a source to perform the steps of: transmitting a message to the destination which requests an allocation of a specified number of credits from the destination, a credit manifesting a portion of memory space in the destination that has been set aside to store a received packet; updating a stored credit value at the source upon receipt of a message from the destination which grants at least some of the requested credits; and transmitting a packet or packets from the source to the destination and decrementing the stored credit value for each transmitted packet. The source also includes means for transmitting a packet debit command which returns to the destination credits that are no longer required by the source, thus enabling the destination to reallocate the debited credits to another source which wishes to communicate.

Abstract: Upon the adjustment of a control setting of a test instrument, the current data (taken before the change is effected) is manipulated by recalculating the trace data in light of any adjustment that is entered by a user. This represents an estimate of the effect of the adjustment in the control setting, and this estimate is redrawn on a display device. This modified image is preferably displayed before the real new image is ready to be displayed. This provides immediate feedback to the user so that adjustments can be effected without slowing the measurement process. Various embodiments provide panning or repositioning the trace left and right while changing the x-axis center frequency; stretching or compressing the trace (spanning) while changing the frequency span; or using a combination for adjustments to only the start or stop frequency. In one embodiment, the estimate can be displayed only after the user has committed to having a new measurement performed.