Today many instances of IEEE 1149.1 Tap domains are included in integrated circuits (ICs). While all TAP domains may be serially connected on a scan path that is accessible external to the IC, it is generally preferred to have selectivity on which Tap domain or Tap domains are accessed. Therefore Tap domain selection circuitry may be included in ICs and placed in the scan path along with the Tap domains. Ideally, the Tap domain selection circuitry should only be present in the scan path when it is necessary to modify which Tap domains are selected in the scan path. The present invention describes a novel method and apparatus which allows the Tap domain selection circuitry to be removed from the scan path after it has been used to select Tap domains and to be replaced back into the scan path when it is necessary to select different Tap domains.
This application claims priority under 35 USC .sctn. 119(e)(1) of provisional application No. 60/517,250, filed Nov. 4, 2003.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is related to 1) application Ser. No. 08/918,872, filed Aug. 26, 1999, now U.S. Pat. No. 6,073,254, "Selectively Accessing Test Access Ports in a Multiple Test Access Port Environment", which is hereby incorporated by reference, 2) application Ser. No. 09/458,313, filed Dec. 10, 1999, now U.S. Pat No. 6,324,614, issued Nov. 27, 2001, "TAP With Scannable Control Circuit For Selecting First Test Data Register In TAP Or Second Test Data Register In TAP Linking Module For Scanning Data", which is hereby incorporated by reference, 3) application Ser. No. 09/277,504, filed Mar. 26, 1999, now U.S. Pat. No. 6,324,662, issued Nov. 27, 2001, "A TAP and Linking Module for Scan Access of Multiple Cores with IEEE 1149.1 Test Access Ports", which is hereby incorporated by reference, and 4) application Ser. No. 60/207,691, filed May 26, 2000, now U.S. Pat. No. 7,058,862, issued Jun. 6, 2006, "Selecting Different 1149.1 TAP Domains From Update-IR State", which is hereby incorporated by reference. This application claims priority under 35 USC 119(e)(1) of provisional patent application Ser. No. 60/517,250, filed Nov. 4, 2003.
