摘要:
The high speed line adapter comprises a bit handling layer (34,46) and a byte handling layer (36,50) and a receive queue mechanism (48).The bit layer receives the frames from the high speed line 9. It performs the SDLC protocol, it removes the flag and BCC characters and adds one ending condition control character which indicates whether the frame was correctly received or not. It causes the address and control fields, the data if any and the ending condition character to be stored into a receive queue buffer at the first free address. The byte layer 50 takes out the frame characters from the receive queue as soon as a pool buffer is available in the memory of the central unit of the communication controller. It sends the data if any to said memory through a direct access memory bus and sends the address and control fields and the ending condition to the microprocessor of the adapter.The provision of the receive queue mechanism allows high speed lines to be connected to a communication controller, without modifying its network control program.
摘要:
In a data communication system, a device for performing a wrap test on at least one line without affecting the other lines that transmit and receive data over at least one multiplex link (4) within time slots allocated to a given line within a given frame. During each time slot, a wrap control bit (W) is set by the communication system to a state that indicates either the wrap test mode or the normal mode of operation. Said bit controls a logic circuit (51) to cause data to be sent either over line (4) or to the receive circuit to perform the test, within each time slot.
摘要:
The disclosed circuit employs a single programmable timer and address decoder which identifies a plurality of bursts received from other stations in a TDMA communications network by means by identifying their origin addresses, and then starts associated timing intervals in the programmable timer for each burst. The instant when the intervals being timed terminate, corresponds approximately to the instant at which the local station should commence its transmission burst. The programmable timer and synchronizer associates each of a plurality of timing intervals with each of the plurality of transmitting stations in the TDMA network, and terminates each respective interval at approximately the same instant in a given local station, thus allowing the time for commencement of the local station's transmission burst to be reliably determined without regard for the participation of any more than one other of the plurality of transmitting stations in the TDMA network. This enables a TDMA communications system to be democratically synchronized in a reliable manner.