Tech Arsenal 1/Tech Arsenal (Arsenal Computer).ISO/tek-21/qemm7ref.zip/STEALTH.TEC

Text File | 1993-06-08 | 17KB | 376 lines

                 Troubleshooting Stealth ROM


  This QEMM 7 technote is an abridged version of a technical
  bulletin that is available through our standard support channels.
  The information contained in this version pertains ONLY to QEMM
  version 7.0.  If you need information relating to earlier versions
  of QEMM you can obtain the unabridged version from the following
  sources:

  Quarterdeck Technical Support BBS:  STEALTH.TEC
                         CompuServe:  STEALT.ZIP
                              Q/FAX:  #205


  Subject: Stealth ROM may seem mysterious, but it really is not.
  This technote tells you how to diagnose and solve problems
  related to the use of the Stealth ROM feature of QEMM.


  This document tells you how to diagnose and solve problems
  related to the use of the Stealth ROM feature.  Please review the
  information in PRODUCTS.TEC before beginning the steps outlined
  in this technote.  This technote contains information on various
  hardware and software products that require specific excludes or
  other parameters when used with Stealth ROM, and you may find the
  information you need here.

  If you are reading this technote because QEMM displayed the
  message "CANNOT FIND ROM HANDLER FOR INTERRUPT XX" you should
  instead refer to technote XSTI.TEC which was installed in your
  QEMM\TECHNOTE directory at the time you installed QEMM.


  A SIDE NOTE:
  QEMM's Stealth ROM feature only relocates those ROMs which are
  accessed through the use of interrupts. A ROM that is not
  Stealthed may still have regions that are never used during the
  system's normal operation. Some disk ROMs, video ROMs, and
  devices that only use their ROMs during bootup (before the
  CONFIG.SYS is loaded) fit into this category.  You may be able to
  get more High RAM by INCLUDING these unused regions on the
  QEMM386.SYS device driver line in CONFIG.SYS.  To find out what
  addresses you can include, run an Analysis procedure (explained
  in Chapter 9 of the QEMM manual). Then use the INCLUDE parameter
  to include the addresses (see Chapter 7 of the QEMM manual).


                            SECTION ONE
  STEP ONE:

  The first step is to ascertain whether Stealth ROM is involved
  with the problem.  Remove the Stealth ROM parameter (ST:M or
  ST:F) from the QEMM device line in your CONFIG.SYS file.  Reboot
  your computer and try to duplicate the problem.  If the problem
  still happens, then Stealth ROM is not causing the problem, and
  you should refer to the troubleshooting section of your QEMM
  manual for further information.

  STEP TWO:

  If Stealth ROM is involved in the problem, add Stealth ROM
  parameters ST:M and XST=F000 to the QEMM device line in the
  CONFIG.SYS file.  Your QEMM line would look something like this:

           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M XST=F000

  Reboot the computer.  If this step solves the problem, go on to
  STEP THREE; if it does not, go on to SECTION TWO.

  STEP THREE:

  If XST=F000 solves your problem replace this parameter with
  X=F000-FFFF, reboot your computer, and try again to create the
  problem.  The QEMM line in your CONFIG.SYS file would look
  something like this:

           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M X=F000-FFFF

  If you cannot recreate the problem with the above line, add the
  parameter FSTC to the end of the line as follows:

        DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M X=F000-FFFF FSTC

  and reboot.  If this step solves the problem, continue on.  If it
  does not (and FSTC may not work in all circumstances) then remove
  the FSTC parameter and reboot with the previous QEMM line.  In
  either case, run Manifest (by typing MFT from the DOS prompt) and
  look at the QEMM/Analysis screen.  The last line should look
  something like this:

                    Fn00 IIII IIII IIII IIOO

  The portions of the address space with the O in them are being
  accessed directly.  Some program or piece of hardware is trying
  to read the contents of the ROM here directly, rather than
  accessing them through interrupts.  This portion of the address
  space must be allowed to be accessed directly.  This is done by
  using an EXCLUDE statement to prevent QEMM from mapping memory
  into this area.  In our example the target region is FE00-FFFF.
  The appropriate EXCLUDE is X=FE00-FFFF and the QEMM line would
  look like this:

           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M X=FE00-FFFF

  This EXCLUDE allows Stealth ROM to do its job and costs you only
  8K of High RAM.

  STEP FOUR:

  If XST=F000 solves your problem while X=F000-FFFF does not, try
  using ST:F instead of ST:M.  You may end up with more High RAM
  with ST:F than with ST:M and XST=F000.

                              SECTION TWO

  PLEASE NOTE:  This section is ONLY for users with video ROM.
  Hercules-compatible monochrome and CGA systems do not have video
  ROM; therefore, this section does not apply to users with such
  systems.

  On most systems, the Video ROM is located at C000-C7FF and uses
  32K of upper memory address space.  Some machines have a video
  ROM elsewhere, usually E000-E7FF.  If this is true of your
  system, you should use E000 (or wherever your video ROM begins)
  instead of C000.  IBM PS/2 Micro Channel machines and other Micro
  Channel machines have their video ROM at E000-EFFF; when using
  the XST parameter on such a machine, you would use XST=E000 when
  performing the steps outlined in this section.  See the
  instructions in STEP NINE for the proper use of the XST=E000
  parameter on a Micro Channel machine.

  STEP FIVE:

  If XST=F000 does not solve your problem, try XST=C000.  The QEMM
  line of the config.sys would look like this:

           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M XST=C000

  If XST=C000 does not work, go on to STEP THREE.  If XST=C000 does
  work, go on to STEP SIX.

  STEP SIX:

  If XST=C000 solves the problem, try placing the Page Frame at
  C000.  Do this only if the entire C000 range is available--that
  is, no device is using address space between C000 and CFFF for
  Adapter ROM or RAM.  The QEMM line of the CONFIG.SYS would look
  like this:

           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M FR=C000

  If this works, this may be an acceptable solution.  All the
  address space in which High RAM can be created is being used in
  this configuration.  If this step does not work (or if you cannot
  put the Page Frame at C000) go on to STEP SEVEN:

  If XST=C000 solves the problem but you do not want to put the
  Page Frame at C000 (or cannot for some reason) then try the
  parameter F10:N (or FASTINT10:N) which tells QEMM to allow the
  video ROM's own code to be used.  By default QEMM replaces some
  of the video ROM's code with its own video code.  This parameter
  tells QEMM not to perform this function.  The QEMM line of the
  CONFIG.SYS would look like this:

           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M F10:N

  If this step works, all ROMs are being Stealthed.  (You may
  choose to try STEP EIGHT as an alternative.)  If this step does
  not work, go on to STEP EIGHT.

  STEP EIGHT:

  If XST=C000 solves the problem but FR=C000 or FASTINT10:N does
  not (or you either cannot put the Page Frame at C000 or do not
  want to use FASTINT10:N) then replace XST=C000 with X=C000-C7FF.
  The QEMM line of the config.sys would look like this:

           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M X=C000-C7FF

  If this works, add the parameter FSTC to the QEMM line:

       DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M X=C000-C7FF FSTC

  Reboot your computer.  If this step works, continue on; if this
  step does not work (and FSTC may not work in all circumstances)
  then remove the FSTC parameter and reboot with the previous QEMM
  line.

  In either case, run Manifest (by typing MFT at the DOS prompt)
  and look at the QEMM/Analysis screen.  The Cn00 line should look
  something like this:

                       Cn00 OIII IIII OOOO OOOO

  This indicates that the first 4K region of the C000 range (in the
  video ROM) is being accessed directly.  This portion of the
  address space must be EXCLUDED from QEMM's use when Stealth ROM
  is enabled.  The appropriate QEMM line in the CONFIG.SYS would
  be:

           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M X=C000-C0FF

                             SECTION THREE
  STEP NINE:

  On some machines there are other ROMs that can be Stealthed;
  often these are disk ROMs.  The same procedure would be used for
  troubleshooting a disk-related problem.  That is, add XST=??00
  (using the beginning address of that particular ROM.)  If this
  solves the problem, replace the XST=??00 with the appropriate
  EXCLUDE (X=??00-!!FF, replacing ??00 and !!00 with the beginning
  and ending addresses of the ROM) to determine whether the problem
  is related to Stealthing or to the fact that some portion of the
  ROM's address space needs to be directly accessible.  The trick
  of making the Page Frame begin at the beginning of the disk ROM
  may also work here as well.

  If XST=??00 solves your problem, try replacing it with FR=??00
  (as long as there is a 64K portion of the address space free
  beginning at ??00 and that ?? is a multiple of 16.)  If some
  portion of the address space must be EXCLUDED for Stealth ROM to
  work you should check Analysis with the FSTC and X=??00-!!FF
  parameters on the QEMM line.

  Because of the way the ROMs are written for the IBM PS/2 machines
  and, perhaps, other Micro Channel machines, it is necessary to
  load HOOKROM.SYS before QEMM386.SYS in the CONFIG.SYS for
  XST=E000 to work.  For example:

           DEVICE=C:\QEMM\HOOKROM.SYS
           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M XST=E000

  STEP TEN:

  Use XST=F000, XST=C000, and XST=??00 simultaneously for all ROMs
  being Stealthed.  Then replace the XSTs one by one with the
  appropriate regular Exclude (X=F000-FFFF, X=C000-C7FF, X=??00-
  !!FF...) and look at the QEMM/ Analysis screen of Manifest to see
  what portions of the address space need to be directly available.

  STEP ELEVEN:

  If ST:M with XST on all Stealthed ROMs fails, add the following
  parameters to the QEMM line we used in STEP TEN:

              FB:N UFP:N VHI:N F10:N

  If this works, remove the XSTs one at a time to determine which
  one(s) you actually need.  If an XST alone does not solve the
  problem, turn back to SECTION ONE for help in determining the
  appropriate XST or EXCLUDE while keeping the above parameters.
  The parameters are explained further in the longer, unabridged
  version of this technote as well as in your QEMM manual.

  STEP TWELVE:

  If ST:M does not work, try ST:F instead.  If ST:F does not work,
  try ST:F XST=C000 (and XST=??00) for Stealthed ROMs other than
  the one(s) overlain by the Page Frame.

  STEP THIRTEEN:

  If none of these steps solves the problem, Quarterdeck's Testing
  and Compatibility Department want to know what program or device
  is failing (and at what point.)  Please contact our Technical
  Support staff so that our technicians can get all the necessary
  information about your problem.


  ADDITIONAL INFORMATION ABOUT STEALTH ROM AND RELATED ISSUES:

  1) WHAT ARE ADVANCED DISK FEATURES AND VHI:N?

  The BIOS has a set of function calls intended for use by
  multitasking programs.  These are Int 15, functions 90 and 91.
  The system ROM or disk ROM may issue the Int 15, fn 90 call while
  it is waiting for the disk controller to read or write a sector,
  allowing other programs to execute during this wait.  When the
  sector is ready, the disk interrupt handler issues an Int 15, Fn
  91, signaling the multitasking program that the disk information
  is ready to be processed by the system or disk ROM.

  Some disk caches hook this call to allow your system to go ahead
  and execute your current program while the system or disk ROM is
  waiting for its requested sector.  Whereas these caches preserve
  the stack and register state for the BIOS and the application
  when doing this pseudo-multitasking, they do not preserve the
  mapping of the page frame.  Therefore, if the BIOS uses the Page
  Frame itself (as does Stealth ROM), this could generate conflicts
  and system failures.  Since no known disk cache does the proper
  Page Frame preservation, QEMM automatically suppresses INT 15,
  function 90 calls from the BIOS, effectively disabling advanced
  disk features.  Caches that save and restore the Page Frame when
  using advanced disk features can use a programming interface to
  QEMM to re-enable advanced disk features.

  You may defeat QEMM's defeating of this feature with the
  VIRTUALHDIRQ:N (VHI:N) parameter on the QEMM device line in your
  CONFIG.SYS file.  If your cache has these "Advanced Features" and
  does not save and restore the Page Frame you will crash or
  corrupt data on the cached drive(s).

  2)  CAN I LOAD A DRIVER THAT USES ROM BEFORE QEMM?

  You can load a device driver that uses a ROM before QEMM and
  still Stealth that ROM by loading the driver HOOKROM.SYS before
  you load this driver. HOOKROM is installed in your QEMM
  directory.  Here is an example of a CONFIG.SYS file that loads
  HOOKROM, then a driver that uses a ROM, then QEMM with Stealth
  ROM enabled:

           DEVICE=C:\QEMM\HOOKROM.SYS
           DEVICE=C:\????????.SYS
           DEVICE=C:\QEMM\QEMM386.SYS RAM ST:M

  3)  WHY DOES XST=E000 ONLY WORK ON PS/2 MACHINES IF I USE
      HOOKROM.SYS?

  The code in the E000-EFFF portion of the ROM on PS/2 (and perhaps
  other Micro Channel machines) is not directly pointed to by the
  interrupt table.  The interrupt table points to addresses in
  F000-FFFF, which then point to the appropriate code in the E000-
  EFFF segment.  You can see this in the FirstMeg/ Interrupts
  section of Manifest.  When you load HOOKROM.SYS, it traces down
  the redirection of the interrupts to the place where the
  executing code begins, so that interrupts that are serviced by
  code in the E000-EFFF segment actually point to addresses in the
  E000-EFFF segment.  The use of HOOKROM.SYS is discussed in STEP
  NINE of the troubleshooting section of this technote.

  4)  WHY DOES MY COMPUTER'S SETUP PROGRAM NOT COME UP WHEN ST:M
      IS ENABLED?

  Some machines have a built-in System Setup program in the BIOS
  ROM that can be popped up at any time.  Using Stealth ROM might
  make this feature inaccessible to you after your system has
  booted.  Because the Setup program accesses the ROM directly, you
  must EXCLUDE the portion of address space where it is stored in
  order for it to work after QEMM has been loaded and Stealth ROM
  enabled.  On most machines this Setup program is found in F000-
  F7FF.

  You may decide that you would rather have access to the Setup
  program ONLY on bootup and use this portion of the address space
  for High RAM.  Since you must reboot your computer after making
  changes in your CMOS Setup anyway, most users consider this a
  fair trade.

  SUMMARY:

  The Stealth ROM technology has been exhaustively tested; however,
  due to the wide variety of software and hardware in the PC world,
  it cannot be guaranteed to work with every configuration.  The
  actual Stealthing of interrupts is very successful.  The most
  common failures are due to programs (or other ROMs) trying to
  access a portion of the ROM directly, rather than by means of
  interrupt.

  If you are interested in a longer, highly technical explanation
  of Stealth ROM, read the unabridged version of this technical
  bulletin, available through our standard support channels.  See
  CONTACT.TEC in your QEMM\TECHNOTE directory for information on
  obtaining technotes.

  If you experience a problem that you are unable to resolve using
  the steps outlined in this technical bulletin, Quarterdeck would
  very much like to hear about it.

  ****************************************************************
  This technical note may be copied and distributed freely as long
  as it is distributed in its entirety and it is not distributed
  for profit.  Copyright (C) 1991-3 by Quarterdeck Office Systems
  ******************* E N D   O F   F I L E **********************