Compaq EV68A Power-Up Self-Test and Initialization, Built-in Self-Test, Srom Initialization

Power-Up Self-Test and Initialization

Figure 11–1 TestStat_H Pin Timing During Power-Up Built-In Self-Test (BiST)

ClkFwdReset_L

Tbox_Reset_A_L

TBox Reset Engine Idle DoBist DoResult DoSROM Idle

TestStatus_H

BiSTResult BiSTResult OR T

LKG-10950A-98WF

Figure 11–2 TestStat_H Pin Timing During Built-In Self-Initialization (BiSI)

Tbox_Rst_A_L1

TBox Reset Engine1	Idle	DoMfgSelfinit	Idle
TestStatus_H1			TimeOut
ClkFwdRst_L1
			LKG-10951A-98WF

11.5 Power-Up Self-Test and Initialization

Upon powering up, the 21264/EV68A automatically performs the self-test of all major embedded RAM arrays and then loads the Cbox configuration registers and the instruc- tion cache from the system SROM. The chip’s internal logic is held in reset during these operations. See Chapter 9 for sequencing of power-up operations.

11.5.1 Built-in Self-Test

The power-up self-test is performed on the instruction cache and tag arrays, the data cache and tag arrays, the triplicate tag arrays, and the various RAM arrays located in the branch history table logic. The power-up self-test lasts for approximately 700,000 CPU cycles. The result of self-test is made available as Pass/Fail status on the TestStat_H pin (see Section 11.4).

The result of self-test is also available in an IPR bit. Software can read this status through IPR I_CTL(23) (0 = pass, 1 = fail). See Section 5.2.15.

The power-up BiST leaves all bits in all arrays initialized to zeroes. The instruction cache and the tag are reinitialized as part of the SROM initialization step. This is detailed in Section 11.5.2.

11.5.2 SROM Initialization

Power-up initialization on the 21264/EV68A is different from previous generation Alpha systems in two aspects. First, in the 21264/EV68A systems, the presence of serial ROMs is mandatory as initialization of several Cbox configuration registers depends on them. Second, it is possible to skip or partially fill Icache from serial ROMs. Figure 11–3shows the map of the data in serial ROMs.

21264/EV68A Hardware Reference Manual Testability and Diagnostics 11–5