TA # Date Created Date Updated   Printer Friendly Version of This TA   Print Article
  E-mail This TA   E-mail Article
106313 10/18/1990 03:07 PM 11/26/1990 06:12 PM
Cannot install because system reboots or screen blanks at Boot:.
Keywords
reboots n1 prompt ega vga install adapter compaq olivetti ibm autoswitch hangs xenix
Release
SCO XENIX System V Operating System Generic
SCO UNIX System V/386 Operating System Generic

Problem
          Cannot install the SCO XENIX Operating System because the
          computer always reboots from the N1 or screen blanks after
          pressing <Return> at the Boot: prompt.

CAUSE:
        There are two known causes for this problem:

          (1) An improperly configured EGA adapter

           (2) an incompatible VGA adapter.


Solution
           If the user has an EGA adapter, it may simply be incompatible with 
            SCO XENIX.  Also it is possible that the switches on the EGA are 
            set incorrectly.  If the card has an AUTOSWITCH feature, it must 
            be turned off.  The user should also experiment with the
           EGA/CGA/MONOCHROME switches.

           If the user has a VGA adapter, and is running an operating system
            prior to SCO XENIX Release 2.2.3, the adapter will not work 
            regardless of what graphics mode it is set to. Only the Compaq VGA 
            is supported under SCO XENIX Release 2.2.3, and then only under EGA
            mode.  There is a Support Level Supplement that provides EGA support
            for the IBM and Olivetti VGA cards running SCO XENIX Release 2.2.3.
            If you have SCO XENIX 386 Operating System, request SLS xnx086.  If 
            you have SCO XENIX 286 Operating System Release 2.2 and above, re-
            quest SLS xnx084.  These SLS's contain a new set of N volumes.

            It is sometimes confusing to users how it could be a video card
            problem when the 'boot colon' prompt is printed correctly.  The
            reason that this can succeed, while the boot up sequence fails, 
            is that up until a certain point the /boot program is using bios
            calls to print out the information that appears on the screen.
            At that point, the kernel is completely loaded and is then
            invoked.  Console output is then done under the control of the
            kernel console device driver.  The driver expects certain
            behavior from the card.  The video cards listed in the Release
            Notes conform to the behavior that the device driver expects.
            The point at which the kernel takes over console output using the
            console driver is easily observed.

                     For SCO XENIX, at the boot: prompt, type:

                              boot: xenix prompt="Now switching--press RETURN"


                     For SCO UNIX, at the boot: prompt, type:

                              boot: unix prompt="Now switching--press RETURN"

            If, upon booting, the above prompt is printed and the screen 
            clears or exhibits other abnormal behavior when <Return> is 
            pressed, then the problem is occurring at the exact point at 
            which the kernel takes over the hardware.  This would imply a 
            video card incompatibility.
            
SEE ALSO:
          The Release Notes for the version of SCO XENIX or SCO UNIX System
           V/386 that is installed.


Back to Search ResultsBack to Search Results