2.2 The IBM 7171 ASCII Device Attachment Control Unit - Index of

Chapter 7. IBM 7171 Diagnostics7.1 Diagnostics OverviewThis section describes IBM 7171 Resident Diagnostics which are run when theIBM 7171 power is turned on. The power-on sequence automatically starts theexecution of the Basic Assurance Diagnostic Tests (BAT) contained in ROMslocated on the CC board, the CPU board and each TC board. Successful completionof the Diagnostic Tests results in the system becoming operational and theIBM 7171 Ready light being turned on. Error conditions are indicated by lights onthe TC boards, the CPU board, and the CC board.7.2 System DescriptionFigure 7 -1 below shows the manner of invoking diagnostics.ALWAYS EXECUTED BY POWER-ON(MICROCODE IN ROS)reP!~fTC!~P CPU,TC,CCH INVOKEDA SEPARATELYSECAINVOKED BYCC~ _________ ~-'I~_~_~_U_T_O ___ ~PHASE CPU CONTROLS2 CROSS CARDTESTSFigure 7-1.Power-on Basic Assurance Test)Basic assurance tests are run in two phases. In the first phase tests are conductedwithin each board containing a microprocessor (the CC board,the CPU board andthe TC boards). These tests cover hardware internal to each Customer ReplaceableUnit (CRU) containing a microprocessor except for the CC which also teststhe CA board. In the second phase, cross board tests are under control of the CPUboard which checks the interface between it and the TC boards and between it andthe CC board.Chapter 7. mM 7171 Diagnostics 7 -1