Abstract: A printing system wherein pre-printing commands, print data, and post-printing commands are nested in a data stream, the commands bounding a group of print data pages in the data stream, the group of pages containing one or more page data blocks, and the commands defining one or more operations to be performed relative to the group of pages. Groups of pages are handled in accordance with the commands in the data stream, and the commands are buffered while a print processor processes the group of pages to form printed sheets therefrom.

Abstract: A common memory interfacing circuit and method for coupling a memory to either a synchronous bus or an asynchronous bus. Synchronizing means are provided for synchronizing memory request signals with a local clock when the interfacing circuit is coupled to an asynchronous bus. The interface circuit responds to signals from the memory when internal memory operation has been completed and generates an acknowledge signal to send to the requesting bus. To simplify the common interface circuit, a synchronous protocol for information exchange between system components is made similar to an asynchronous protocol.

Abstract: A document distribution terminal is organized with two supervisory processing units, one to control the data entry and data printing and the other to control the terminal. Each of these processing units only performs control functions. All of the data processing is performed by various specialized devices preparing the document data for transmission or for printing. Further, the terminal is organized with two interfaces and an adapter coupling the two interfaces. The terminal-controlling processing unit supervises one interface that interconnects all of the specialized devices. The other processing unit, that controls the data entry and data printing devices, supervises the second interface. Once the supervisory processing units have set up a job in the terminal, the data transfer across the two interfaces is substantially under the control of logic in the adapter.

Abstract: A buffer storage apparatus has two buffers alternating between receiving and supplying data signals. The buffer functions are alternated between the buffers when one of the buffers is empty and another one of the buffers has received a predetermined number of signals even though that data-receiving buffer is not yet full. With data transferred in blocks of data bytes, switching between buffers occurs on the predetermined address boundaries of the data blocks. Alternation of functions between the buffers can occur at any one of a plurality of address boundaries within the data-receiving one of the buffers. By using a plurality of such buffer storage apparatus to connect individual data burst units to a plural-port high-speed common unit, each data burst unit has a high speed buffered access to the high speed common unit.