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21264/EV68A Hardware Reference Manual
Testability and Diagnostics 11–1
11
Testability and Diagnostics
This chapter describes the 21264/EV68A user-oriented testability and diagnostic fea-
tures. These features include automatic power-up self-test, Icache initialization from
external serial ROMs, and the serial diagnostic terminal port.
The boundary-scan register, which is another testability and diagnostic feature, is listed
in Appendix B. The boundary-scan register is compatible with IEEE Standard 1149.1.
This chapter is organized as follows:
• Test pins
• SROM/serial diagnostic terminal port
• IEEE 1149.1 port
• TestStat_H pin
• Power-up self-test and initialization
• Notes on IEEE 1149.1 operation and compliance
The 21264/EV68A has several manufacturing test features that are used only by the
factory, and they are beyond the scope of this chapter.
11.1 Test Pins
The 21264/EV68A test access ports include the IEEE 1149.1 test access port, a dual-
purpose SROM/Serial diagnostic terminal port, and a test status output pin. Table 11–1
lists the test access port pins.
Table 11–1 Dedicated Test Port Pins
Pin Name Type Function
Tms_H Input IEEE 1149.1 test mode select
Tdi_H Input IEEE 1149.1 test data in
Trst_L Input IEEE 1149.1 test logic reset
Tck_H Input IEEE 1149.1 test clock
Tdo_H Output IEEE 1149.1 test data output
SromData_H Input SROM data/Diagnostic terminal data input