pmodew.faq

来自「开放源码的编译器open watcom 1.6.0版的源代码」· FAQ 代码 · 共 122 行

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------------------ Frequently Asked Questions About PMODE/W ------------------
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----------------------------- Updated 11/18/96 -------------------------------
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Q: Where can I find the latest version of PMODE/W?

A: The best way to get the latest version is via the Internet. We always place
   the newest PMODE/W on the following sites. The sites toward the top are
   most likely to have it first:

   ftp://ftp.cdrom.com/pub/demos/incoming/code
   (later moved to /pub/demos/code/pmode)
   ftp://x2ftp.oulu.fi/pub/msdos/programming/watcom

   You can get the latest release (as well as other information) via WWW at:

   http://www.di.net/pmw
   http://www.dorsai.org/~daredevi/pmw

   In addition, you may contact the authors directly by sending email to
   [e-mail].


Q: How do I get rid of the startup message? How come it was never there before?

A: You can disable the startup message using PMWSETUP. The startup message
   was just added in v1.23 at the request of many PMODE/W users. We did not
   feel a need to display anything at startup, but since so many have asked
   for it, we decided to add it in this version.


Q: Is PMODE/W 100% compatible with DOS/4GW?

A: PMODE/W is compatible with nearly all Watcom C/C++ functions. However,
   PMODE/W does not support all of the extensions and API functions which
   DOS/4GW does. DOS/4GW does a number of things that we feel are quite
   unnecessary for most applications and most likely you will never miss them
   (especially since they waste a lot of your precious memory and disk space).
   Why extend something, wasting system resources, when you may not even be
   using it in your program? So remember: before blaming a problem with your
   program on PMODE/W, make sure that what you are doing is indeed supported
   by our system. Read PMODEW.DOC for more information.

   NOTE: PMODE/W is NOT a clone of DOS/4GW! There are many differences in the
         way PMODE/W operates. Please keep this in mind when reporting bugs.


Q: Why doesn't my PMODE/W program work with DOS/4GW?

A: You can not run a compressed PMODE/W program with DOS/4GW. The program may
   be using a DPMI function which PMODE/W supports but DOS/4GW does not. You
   may also be using 16 bit code directly instead of allocating DOS memory,
   copying the code, and using it. PMODE/W always loads 16 bit real mode code
   into low memory, thus enabling you to use it directly. DOS/4GW loads all
   code into extended memory, where you can not use real mode code.


Q: Why doesn't my DOS/4GW program work with PMODE/W?

A: Almost any program that works with DOS/4GW will run correctly with PMODE/W
   as long as it does not use any DOS/4GW specific functions. If a program
   does not work at first, you may have to tweak the PMODE/W system variables
   using PMWSETUP. For example, you may try setting the maximum low memory to
   reserve to 0FFFFh to force PMODE/W to load all 32 bit code and data into
   extended memory like DOS/4GW (16 bit code will still be loaded into low
   memory). You may also try increasing the number and/or nesting of the
   protected and real mode stacks.


Q: Can I still debug PMODE/W programs under the Watcom debugger?

A: Yes you can. You can debug your PMODE/W programs in exactly the same manner
   you would debug a DOS/4GW program (using the /TR=RSI switch of course). You
   cannot, however, debug programs which have been compressed using PMWLITE.
   You also cannot debug PMODE/W programs that do not run under DOS/4GW.


Q: Why can't I access more than 16 megs of memory under my VCPI server when
   there is more than that available in my system?

A: You must increase the maximum number of VCPI page tables PMODE/W will
   manage using the PMWSETUP program. Each page table you add will give you
   another 4 megs of memory (provided that it is physically available of
   course).


Q: Why can't I map more than 4 megs of address space of a physical device
   using DPMI function 0800h?

A: You must increase the maximum number of physical address mapping pages in
   PMODE/W using PMWSETUP.


Q: How come PMODE/W takes a little while to load under EMM386?

A: PMODE/W allocates all of its extended memory pool during initialization
   whereas DOS/4GW allocates memory every time you (or the C libraries) call
   the DPMI memory allocation functions. The delay is caused by EMM386's
   slowness in allocating pages. PMODE/W may take a little longer than DOS/4GW
   at startup in this case, but it will be much faster during the execution
   of the program since it does not need to call EMM386 for memory again
   after that. If the delay is a problem, you can adjust the amount of
   extended memory to allocate in PMWSETUP. The less memory there is to
   allocate, the faster loading will be under EMM386. However, keep in mind
   your memory requirements when changing that setting.


Q: How come DOS/4GW, Pharlap, or other 32bit DOS applications don't work using
   spawn() under PMODE/W?

A: Some other DOS extenders require extended memory to initialize. Also, the
   program you are trying to run may require extended memory. To remedy this,
   you can change the maximum amount of extended memory for PMODE/W to
   allocate using PMWSETUP. Set the value to something you feel meets the
   requirements of your program instead of the default (which allocates ALL
   memory). This will make sure that your program does not allocate any more
   memory than it needs, therefore leaving whatever memory is left over for
   the program you are trying to execute.