1. xerox 560 computer system - The UK Mirror Service

change the rate on the primary console to retain parallelcontrol. The alternate {local) device creates a log of allSCC transactions. The normal (log) output on I/O subchannelX'OB' is suspended for the duration of the SCCassignment to the remote channel (REMOTE CHANNELswitch in SCC position; ALTSEL switch in OFF position).CONTROL COMMANDSA set of commands and display formats implements operatorcommunication with hardware through the System ControlConsole. These hardware-control commands, called II SCCFunctions ll , are independent, direct hardware controls asdistinguished from the software-level operating controlsactivated from the SCC through the normal I/o system. Aspecial micro-processor, working independently of theBP, senses and controls the execution of SCC functions.The flexibility of character-oriented communications equipmentand micro-programmed control significantly enhancemany system operating and diagnostic features.The basic command format provides a four-level interlockon critical system controls by requiring a correct fourcharactersequence to initiate a command action. In addition,context analysis is provided to assure that commandsare executed only in appropriate system states. Thisbasic format requires that each command is preceded by theIIcontrol-Z II character (control and Z keys depressed simultaneously).Note that within this text, the control-Z characteris represented wi th the symbol II ZCII .A typical command sequence is to enter IIZ C HLTII from theSCC. The system responds by printing II (HLT)II on the nextline of the SCC printout, and forcing the system to haltinstruction execution and enter the IDLE state. If a commandcannot be executed due to improper syntax or context,the system provides an odvisory message following the commandecho indicating the probable source of error. A typicalexample of the display format is II(RSY) *EVENT A1*1I,indicating that a reset command may not be executed priorto halting instruction execution. (Refer to Table 21 fora complete listing of event messages.)The various control functions that may be exercised fromthe SCC may be generally classified into three categories:operator control commands, diagnostic control commands,and maintenance control commands.OPERATOR CONTROL COMMANDSThese commands provide controls which an operator normallyuses to control the computer system. By enteri ng the appropriatecommand the operator may direct the computer systemto load, run, halt, reset, read/set the sense switches, orissue a IIconsole interrupt ll to the operating software.The sense switch control and console interrupt commandsmay interact with the software and are always operative.All other SCC functions may be enabled or disabled bythe SCC FUNCTIONS switch on the SCPoTable 21.Event MessagesDisplay*EVENT 00**EVENT AO**EVENT A1**EVENT A2**EVENT M**EVENT A8**EVENT FO**EVENT Fl**EVENT F4**EVENT F6**EVENT F9*SignificanceSystem Initialization; POWER ON or SUPER RESET.cImproper syntax for Z format command.Command not executed; Improper syntax or system may not be in IDLE mode.Command not executed; system not in maintenance mode.Command not executed; SCC FUNCTION switch is in DISABLE position.Power ride through; recoverable power line fai lure detected; power on trap requested.Trap requested occurred; inhibited in P-Mode.Basic processor error halt; watchdog timeout reset issued when watchdog timeout alarm bitset. (See II Processor Control Word ll .)Basic processor halt; Address Halt.Basic processor halt; Processor-Detected Fault (PDF).System failed micro-diagnostic test (followed by Single Clock Status Register display of theelement that fa i led).Control Commands 153