A VLSI link-level controller

THIS PAPER WILL DISCUSS an IC that performs complete link-level control according to a communication protocol that is a superset of the CCITT X.25 level 2 LAPB protocol because it includes the exchange identification frames. In addition to the standard modulo 8 frame sequencing and 16b CRC error detection method set forth by the protocol, the circuit affords a programmable window size (K) comparator, programmable information field length (Nl) and retransmission (N2) counters, and four programmable link assurance timers (T1 through T4)