摘要:
A serial simplex switch 14 design is provided which includes I/O ports 20 each of which is configurable specifically for attachment to a data communications subsystem 12 or, alternatively, for cascaded connection to a similarly configured I/O port 20 on another switch 14. The switch 14 provides a packet routing function including input 32 and output 36 buffers for each of its I/O ports 20 wherein packets of control messages sent by one subsystem 20 are temporarily stored prior to being delivered to the appropriate destination subsystem 20. When configured to be directly attached to a subsystem 20, the I/O ports 20 separate control messages from incoming integrated data and control message strings. In a cascade configuration, however, a mechanism is provided wherein data and control messages are separated into two physical paths to eliminate the delays associated with integrated data and control message flow through the cascaded I/O port 20. Each I/O port 20 is configurable to either of these methods of operation by means of programmable latches associated with the I/O port 20.
摘要:
A digital data processor acts on a branch and return on address (BAROA) instruction having an operation code field, a memory entry address field and a memory exit address field. The operation code field of the branch and return on address instruction is into an instruction register, the memory exit address field of the loaded branch and return on address instruction is loaded into the address register and the memory entry address field of the branch and return on address instruction is loaded into the program counter. The next sequential address following the address of the current BAROA instruction is then stored in a register stack, and a sequence of instructions starting with the instruction residing at the memory entry address provided by the branch and return on address instruction is fetched and executed. The program counter is incremented each time an instruction is executed. In this manner, the program counter provides the memory addresses of the instructions to be fetched. The memory address in the program counter is compared with the exit address in the address register and loading a return instruction operation code into the instruction register when the memory address in the program counter becomes equal to the exit address in the address register, such return instruction operation code, in turn, causing the address stored in the register stack to be loaded into the program counter.
摘要:
A serial simplex switch 14 design is provided which includes I/O ports 20 each of which is configurable specifically for attachment to a data communications subsystem 12 or, alternatively, for cascaded connection to a similarly configured I/O port 20 on another switch 14. The switch 14 provides a packet routing function including input 32 and output 36 buffers for each of its I/O ports 20 wherein packets of control messages sent by one subsystem 20 are temporarily stored prior to being delivered to the appropriate destination subsystem 20. When configured to be directly attached to a subsystem 20, the I/O ports 20 separate control messages from incoming integrated data and control message strings. In a cascade configuration, however, a mechanism is provided wherein data and control messages are separated into two physical paths to eliminate the delays associated with integrated data and control message flow through the cascaded I/O port 20. Each I/O port 20 is configurable to either of these methods of operation by means of programmable latches associated with the I/O port 20.
摘要:
A digital data processor acts on a branch and return on address (BAROA) instruction having an operation code field, a memory entry address field and a memory exit address field. The operation code field of the branch and return on address instruction is into an instruction register, the memory exit address field of the loaded branch and return on address instruction is loaded into the address register and the memory entry address field of the branch and return on address instruction is loaded into the program counter. The next sequential address following the address of the current BAROA instruction is then stored in a register stack, and a sequence of instructions starting with the instruction residing at the memory entry address provided by the branch and return on address instruction is fetched and executed. The program counter is incremented each time an instruction is executed. In this manner, the program counter provides the memory addresses of the instructions to be fetched. The memory address in the program counter is compared with the exit address in the address register and loading a return instruction operation code into the instruction register when the memory address in the program counter becomes equal to the exit address in the address register, such return instruction operation code, in turn, causing the address stored in the register stack to be loaded into the program counter.