Improvement to Line Scanner Operations in a Communication Controller
Original Publication Date: 1988-Nov-01
Included in the Prior Art Database: 2005-Feb-15
In a communication controller such as the IBM 3725 Communication Controller which comprises a central control unit (CCU) running a network control program, line scanners connected to the central control unit through a bus and an input/output interface (IOC), the line initialization process requires a "get line identification" (GLID) operation. The exchanges on the input/output interface are controlled by tags TD (data tag) and VH (valid halfword). The subject proposal allows the suppression of the delay in the tag operations. The scanner microcode loads the "line identification" into a scanner register before the interrupt to the IOC interface is raised so that when the GLID comes into the scanner, it is completely handled by hardware.