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 11–1lists 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

21264/EV68A Hardware Reference Manual

Testability and Diagnostics 11–1

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Compaq EV68A specifications Testability and Diagnostics, Test Pins, Dedicated Test Port Pins