Control Commands; Operator Control Commands; Event Messages - Xerox 550 Reference Manual

change the rate on the primary console to retain parallel
control. The alternate {local) device creates a log of all
SCC transactions. The normal (log) output on I/O sub-
channel X'OB' is suspended for the duration of the SCC
assignment to the remote channel (REMOTE CHANNEL
switch in SCC position; ALTSEL switch in OFF position).
CONTROL COMMANDS
A set of commands and display formats implements operator
communication with hardware through the System Control
Console. These hardware-control commands, called" SCC
Functions", are independent, direct hardware controls as
distinguished from the software-level operating controls
activated from the SCC through the normal I/o system. A
special micro-processor, working independently of the
BP, senses and controls the execution of SCC functions.
The flexibility of character-oriented communications equip-
ment and micro-programmed control significantly enhance
many system operating and diagnostic features.
The basic command format provides a four-level interlock
on critical system controls by requiring a correct four-
character sequence to initiate a command action. In ad-
dition, context analysis is provided to assure that com-
mands are executed only in appropriate system states. This
basic format requires that each command is preceded by the
"control-Z" character (control and Z keys depressed simul-
taneously). Note that within this text, the control-Z char-
acter is represented with the symbol "Zc".
A typical command sequence is to enter "zc HLP' from the
SCC. The system responds by printing" (HLT)" on the next
line of the SCC printout, and forcing the system to halt
instruction execution and enter the IDLE state.
If a com-
mand cannot be executed due to improper syntax or context,
the system provides an advisory message following the com-
mand echo indicating the probable source of error. A typi-
cal example of the display format is "(RSY) *EVENT A 1 *",
indicating that a reset command may not be executed prior
to halting instruction execution. (Refer to Table 21 for
a complete listing of event messages.)
The various control functions that may be exercised from
the SCC may be generally classified into three categories:
operator control commands, diagnostic control commands,
and maintenance control commands.
OPERATOR CONTROL COMMANDS
These commands provide controls which an operator normally
uses to control the computer system. By entering the appro-
priate command the operator may direct the computer system
to load, run, halt, reset, read/set the sense switches, or
issue a "console interrupt" to the operating software.
The sense switch control and console interrupt commands
may interact with the software and are always operative.
All other SCC functions may be enabled or disabled by
the SCC FUNCTIONS switch on the SCPo
Table 21. Event Messages
Display
*EVENT 00*
*EVENT AO*
*EVENT Al*
*EVENT A2*
*EVENT
M*
*EVENT A8*
*EVENT FO*
*EVENT Fl*
*EVENT F4*
*EVENT F6*
*EVENT F9*
136 Control Commands
Significance
System Initialization; POWER ON or SUPER RESET.
c
Improper 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 failure detected; power on trap requested.
Trap requested occurred; inhibited in P-Mode.
Basic processor error halt; watchdog timeout reset issued when watchdog timeout alarm bit
set. (See" Processor Control Word".)
Basic processor halt; Address Halt.
Basic processor halt; Processor-Detected Fault (PDF).
System fai led micro-diagnostic test (followed by Single Clock Status Register display of the
element that failed).