PC Press 1997 July/Sezamfile97_1.iso/msdos/infoprog/dosprog2.faq

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From: [e-mail] (Jeffrey Carlyle)
Newsgroups: comp.os.msdos.programmer,alt.msdos.programmer,comp.answers,news.answers
Subject: comp.os.msdos.programmer FAQ part 2/5
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Date: 16 Sep 1996 08:25:21 GMT
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Summary: Frequently asked questions by DOS programmers with tested answers.
X-Last-Updated: 1996/03/30
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Archive-name: msdos-programmer-faq/part2
Comp-os-msdos-programmer-archive-name: dos-faq-pt2.txt
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Last-modified: 20 Mar 1996

------------------------------

Subject: comp.os.msdos.programmer FAQ part 2/5

This is part 2 of the frequently asked questions list for the newsgroup
comp.os.msdos.programmer.

Part 2:
  Section 3.  Compile and Link
  Section 4.  Keyboard

------------------------------

Subject: comp.os.msdos.programmer FAQ

comp.os.msdos.programmer FAQ Version 2.06

Copyright 1996 by Jeffrey Carlyle, Stratoware. All rights reserved. This
article is not in the public domain, but it may be redistributed so long
as this notice, the acknowledgments, and the information on obtaining the
latest copy of this list are retained and no fee is charged. The code
fragments may be used freely;  credit would be polite. This FAQ is not to
be included in any static archive (e.g. CD-ROM or book); however, a pointer
to the FAQ may be included.

 =============================
 TABLE OF CONTENTS
 =============================

Part 1:
  Section 1.  General FAQ and Newsgroup Information
  Section 2.  General Reference
Part 2:
  Section 3.  Compile and Link
  Section 4.  Keyboard
Part 3:
  Section 5.  Disks and files
  Section 6.  Serial ports (COM ports)
Part 4:
  Section 7.  Other hardware questions and problems
  Section 8.  Other software questions and problems
Part 5:
  Section 9.  Downloading
  Section 10. Vendors and products

------------------------------

Subject: Section 3.  Compile and link

  <q:3.01> - What the heck is "DGROUP > 64K"?
  <q:3.02> - How do I fix "automatic data segment exceeds 64K" or "stack
             plus data exceed 64K"?
  <q:3.03> - Will Borland C code and Microsoft C code link together?
  <q:3.04> - Why did my program bomb at run time with "floating point
             formats not linked" or "floating point not loaded"?
  <q:3.05> - How can I change the stack size in Borland's C compilers?
  <q:3.06> - What's the format of an .OBJ file?
  <q:3.07> - What's the format of an .EXE header?
  <q:3.08> - What's the difference between .COM and .EXE formats?
  <q:3.09> - How do I create a .COM file?
  <q:3.10> - Where is EXE2BIN located?
  <q:3.11> - What does this message mean: "A20 already enabled so test
             is meaning less?"

------------------------------

Subject: <q:3.01> - What the heck is "DGROUP > 64K"?

    This Q explains the problem; the next Q gives some remedies.

    DGROUP is a link-time group of data segments, and the compiler
    typically generates code that expects DS to be pointing to DGROUP.
    (Exception:  Borland's huge model has no DGROUP.)

    Here's what goes into DGROUP:

    - tiny model (all pointers near):  DGROUP holds the entire program.

    - small and medium models (data pointers near):  DGROUP holds all
      globals and static variables including string literals, plus the
      stack and the heap.

    - large, compact, and huge models in Microsoft (data pointers far):
      DGROUP holds only initialized globals and static variables
      including string literals, plus the stack and the near heap.

    - large and compact models in Borland (data pointers far): DGROUP
      holds initialized and uninitialized globals and static variables
      including string literals, but not the stack or heap.

    - huge model in Borland (data pointers far): there is no DGROUP, so
      the 64K limit doesn't apply.

    In all of the above, which is to say all six models in Microsoft C
    and all but huge in Borland C, DGROUP is limited to 64K including
    string literals (which are treated as static data).  This limitation
    is due to the Intel CPU's segmented architecture.

    For more information, see topics like "memory models" and "memory
    management" in the index of your compiler manual.  Also see
    TI738.asc, downloadable as part of

        <ftp://oak.oakland.edu/pub/msdos/turbo-c/bchelp10.zip>
        <ftp://garbo.uwasa.fi/pc/turbopas/bchelp10.zip>

    for an extended general discussion of memory usage in Borland C
    programs, of which much applies to any C compiler in DOS.

------------------------------

Subject: <q:3.02> - How do I fix "automatic data segment exceeds 64K" or
        "stack plus data exceed 64K"?

    These messages are a variation of "DGROUP > 64K".  For causes,
    please see the preceding Q.

    If you get this error in tiny model, your program is simply too big
    and you must use a different memory model.  If you get this link
    error in models S, C, M, L, or Microsoft's H, there are some things
    you can do.  (This error can't occur in Borland's huge model.)

    If you have one or two big global arrays, simply declare them far.
    The compiler takes this to mean that any references to them will use
    32-bit pointers, so they'll be in separate segments and no longer
    part of DGROUP.

    Or you can use the /Gt[number] option with Microsoft or -Ff[=size]
    with Borland C++ 2.0 and up.  This will automatically put variables
    above a certain size into their own segments outside of DGROUP.

    Yet another option is to change global arrays to far pointers.  Then
    at the beginning of your program, allocate them from the far heap
    (_fmalloc() in Microsoft, farmalloc() in Borland).

    Finally, you can change to huge model (with Borland compilers, not
    Microsoft).  Borland's H model still uses far pointers by default,
    but "sets aside the [64K] limit" and has no DGROUP group, according
    to the BC++ 2.0 Programmer's Guide.  Microsoft's H model does use
    huge data pointers by default but retains DGROUP and its 64K limit,
    so switching to the H model doesn't buy you anything if you have
    DGROUP problems.

------------------------------

Subject: <q:3.03> - Will Borland C code and Microsoft C code link together?

    Typically this question is asked by someone who owns compiler A and
    is trying to write code to link with a third-party library that was
    compiled under compiler B.

    The answer to the question is, Not in general.  Here are some of the
    reasons:

    - "Helper" functions (undocumented functions for stack checking,
      floating-point arithmetic, and operations on longs) differ between
      the two compilers.

    - Extended dictionaries are not compatable between the 2 formats.
      However, the basic structure of both MS and Borland OBJ formats
      is based on the OMF format so specifing that the linker ignore
      the extended dictionary records (/NOE for LINK, -e for TLINK)
      will disable this little hassel.

    - The compilers may embed instructions in the object code that tell
      the linker to look for their own run-time libraries.  You can use
      the linker option that says to ignore such instructions: /n in
      TLINK, /NOD in the Microsoft linker (the one that comes with the C
      compiler, not the one that used to come with DOS).  But getting
      around this problem will very likely just reveal other problems,
      like different helper functions, that have no easy solution.

    Those problems will generate link-time errors.  Others may not show
    up until run time:

    - Borland's compact, large, and huge models don't assume DS=SS, but
      Microsoft's do.  The -Fs option on the Borland compiler, or one of
      the /A options on Microsoft, should take care of this problem--
      once you know that's what's going on.

    - Check conventions for ordering and packing structure members, and
      for alignment of various types on byte, word, paragraph, or other
      boundaries.  Again, you can generally adjust your code to match if
      you know what conventions were used in compiling the "foreign"
      libraries.

    - Check the obvious and make sure that your code was compiled under
      the same memory model as the code you're trying to link with.
      (That's necessary, but no guarantee.  Microsoft and Borland don't
      use exactly the same conventions for segments and groups,
      particularly in the larger memory models.)

    That said, there are some circumstances where you can link hybrids.
    Your best chance of success comes if you compile in large model with
    the compiler switch that says to reload DS on entry to each
    function, avoid longs and floating point, use only 16-bit pointers,
    suppress stack checking, and specify all libraries used in the link.

------------------------------

Subject: <q:3.04> - Why did my program bomb at run time with "floating
        point formats not linked" or "floating point not loaded"?

    These messages look similar but have very different causes.

    "floating point not loaded" is Microsoft C's run-time message when
    the code requires a numeric coprocessor but your computer doesn't
    have one installed.  If the program is yours, relink it using the
    xLIBCE or xLIBCA library (where x is the memory model).

    "floating point formats not linked" is a Borland run-time error
    (Borland C or C++, Turbo C or C++).  Borland's compilers try to be
    smart and not link in the floating-point (f-p) library unless you
    need it.  Alas, they all get the decision wrong.  One common case is
    where you don't call any f-p functions, but you have %f or other f-p
    formats in scanf() or printf() calls.  The cure is to call an f-p
    function, or at least force one to be present in the link.

    To do that, define this function somewhere in a source file but
    don't call it:

        static void forcefloat(float *p) {
            float f = *p;
            forcefloat(&f);
        }

    It doesn't have to be in the module with the main program, as long
    as it's in a module that will be included in the link.

    If you have Borland C++ 3.0, the README file documents a slightly
    less ugly work-around.  Insert these statements in your program:

        extern unsigned _floatconvert;
        #pragma extref _floatconvert

------------------------------

Subject: <q:3.05> - How can I change the stack size in Borland's C
        compilers?

    In Turbo C, Turbo C++, and Borland C++, you may not find "stack
    size" in the index but the global variable _stklen should be there.
    The manual will instruct you to put a statement like

        extern unsigned _stklen = 54321U;

    in your code, outside of any function.  You must assign the value
    right in the extern statement; it won't work to assign a value at
    run time.  The linker may give you a duplicate symbol warning, which
    you can ignore.

    If you are using the Borland PowerPAck for DOS _stklen does not
    change the stack size. To change the stack size you must use STACKSIZE
    in your .DEF file. HEAPSIZE can be used to change the size of your
    program's heap.

------------------------------

Subject: <q:3.06> - What's the format of an .OBJ file?
Date: Wed, 11 Jan 95 15:34:00 CDT

    - base .OBJ format:  Intel's document number #121748-001, {8086
      Relocatable Object Module Formats}.  (not verified)

    Both Microsoft and Borland have extended the .OBJ format, as has IBM
    for OS/2; and according to the MS-DOS encyclopedia, Microsoft
    doesn't actually use all the listed formats.

    - Microsoft-specific .OBJ formats:

      * The .OBJ format document in a text file format, is downloadable
      as <ftp://ftp.microsoft.com/softlib/mslfiles/ss0288.exe>

      * A 45-page article can be found in the {MS-DOS Encyclopedia},
        ISBN 1-55615-049-0, now out of print.

      * "Microsoft Object Module Format (OMF)" Specification, 22 Nov
        1991, was published by the Microsoft Languages Group.  (not
        verified)

    - Borland-specific .OBJ formats:  Open Architecture Handbook.  The
      Borland Developer's Technical Guide, 1991, no ISBN.  Chapter 2,
      "Object file contents", (pages 27-50) covers the comment records
      sent to the object file by Borland C++ version 3.0 and other
      Borland compilers.  The comment records mostly contain information
      for the Borland debugger. (not verified)

    - A "tutorial on the .OBJ format" comes with the VAL experimental
      linker, downloadable as

        <ftp://oak.oakland.edu/pub/msdos/pgmutil/val-link.zip>
        <ftp://garbo.uwasa.fi/pc/assembler/linker.zoo>

      Despite such different names, those files have the same contents,
      but their contents are dated 18 Feb 1989.  You'd be better off
      with one of the more recent references listed above.

------------------------------

Subject: <q:3.07> - What's the format of an .EXE header?

    See PC Magazine 30 June 1992 (xi:12) pages 349-350 for the old and
    new formats.  For a more detailed layout, look under INT 21 AH=4B in
    Ralf Brown's interrupt list <q:2.03>.  That list includes extensions
    for Borland's TLINK and Borland debugger info.

    Among the books that detail formats of executable files are {DOS
    Programmer's Reference: 2d Edition} by Terry Dettman and Jim Kyle,
    ISBN 0-88022-458-4; and {Microsoft MS-DOS Programmer's Reference},
    ISBN 1-55615-329-5.

------------------------------

Subject: <q:3.08> - What's the difference between .COM and .EXE formats?

    To oversimplify:  a .COM file is a direct image of core, and an .EXE
    file will undergo some further relocation when it is run (and so it
    begins with a relocation header).  A .COM file is limited to 64K for
    all segments combined, but an .EXE file can have as many segments as
    your linker will handle and be as large as RAM can take.

    The actual file extension doesn't matter.  DOS knows that a file
    being loaded is in .EXE format if its first two bytes are MZ or ZM;
    otherwise it is assumed to be in .COM format.  For instance, DR-DOS
    6.0's COMMAND.COM is in .EXE format.

------------------------------

Subject: <q:3.09> - How do I create a .COM file?
Date: Fri, 13 Jan 95 15:34:00 CDT

   There are two steps to creating a .COM file. First, your program must
   not have a stack. In C, you must compile your program with the TINY
   memory model. Second, use EXE2BIN or a similiar program to convert
   the .EXE file to a .COM file. To find EXE2BIN see subject: <q:3.10>
   "Where is EXE2BIN located?"

------------------------------

Subject: <q:3.10> - Where is EXE2BIN located?
Date: Fri, 07 Jul 95 15:34:00 CDT

   EXE2BIN was formerly shipped with MS-DOS. If you are still using DOS
   5.0 or earlier you can find EXE2BIN in your DOS directory. Users of
   DOS 6.x need to get the MS-DOS Supplemental Disks. These disks are
   available via FTP at ftp.microsoft.com.

   <ftp://ftp.microsoft.com/peropsys/msdos/public/supplmnt>

------------------------------

Subject: <q:3.11> - hat does this message mean: "A20 already enabled so
        test is meaning less?"

   This message is generated by the DPMIINST program included with older
   versions of Borland C++ and Turbo C++ compilers. Before running
   DPMIINST you must clean boot your computer.

------------------------------

Subject: Section 4.  Keyboard

  <q:4.01> - How can I read a character without echoing it to the screen,
             and without waiting for the user to press the Enter key?
  <q:4.02> - How can I find out whether a character has been typed, without
             waiting for one?
  <q:4.03> - How can I disable Ctrl-C/Ctrl-Break and/or Ctrl-Alt-Del?
  <q:4.04> - How can I disable the print screen function?
  <q:4.05> - How can my program turn NumLock (CapsLock, ScrollLock) on or
             off?
  <q:4.06> - How can I speed up the keyboard's auto-repeat?
  <q:4.07> - What is the SysRq key for?
  <q:4.08> - How can my program tell what kind of keyboard is on the
             system?
  <q:4.09> - How can I tell if input, output, or stderr has been
             redirected?
  <q:4.10> - How can I increase the size of the keyboard buffer?
  <q:4.11> - How can I stuff characters into the keyboard buffer?

------------------------------

Subject: <q:4.01> - How can I read a character without echoing it to the
        screen, and without waiting for the user to press the Enter key?

    The C compilers from Microsoft and Borland offer getch() (or
    getche() to echo the character); Turbo Pascal has ReadKey.

    In other programming languages, execute INT 21 AH=8; AL is returned
    with the character from standard input (possibly redirected).  If
    you don't want to allow redirection, or you want to capture Ctrl-C
    and other special keys, use INT 16 AH=10; this will return the scan
    code in AH and ASCII code (if possible) in AL, but  AL=E0 with AH
    nonzero indicates that one of the grey "extended" keys was pressed.
    (If your BIOS doesn't support the extended keyboard, use INT 16 AH=0
    not 10.)

------------------------------

Subject: <q:4.02> - How can I find out whether a character has been typed,
        without waiting for one?

    In Turbo Pascal, use KeyPressed.  Both Microsoft C and Turbo C offer
    the kbhit() function.  All of these tell you whether a key has been
    pressed.  If no key has been pressed, they return that information
    to your program.  If a keystroke is waiting, they tell your program
    that but leave the key in the input buffer.

    You can use the BIOS call, INT 16 AH=01 or 11, to check whether an
    actual keystroke is waiting; or the DOS call, INT 21 AH=0B, to check
    for a keystroke from stdin (subject to redirection).  See Ralf
    Brown's interrupt list <q:2.03>.

------------------------------

Subject: <q:4.03> - How can I disable Ctrl-C/Ctrl-Break and/or
        Ctrl-Alt-Del?

    Several utilities are downloadable from /pub/msdos/keyboard at
    SimTel.  In that directory, cadel.zip contains a TSR (with source
    code) to disable those keys.  Also, keykill.arc contains two
    utilities:  keykill.com lets you disable up to three keys of your
    choice, and deboot.com changes the boot key to leftShift-Alt-Del.

    C programmers who simply want to make sure that the user can't Ctrl-
    Break out of their program can use the ANSI-standard signal()
    function; the Borland compilers also offer ctrlbrk() for handling
    Ctrl-Break.  However, if your program uses normal DOS input such as
    getch(), ^C will appear on the screen when the user presses Ctrl-C
    or Ctrl-Break.  You can avoid the ^C echo for Ctrl-C by using
    _bios_keybrd() in MSC or bioskey() in BC++; however, Ctrl-Break will
    still terminate the program.

    An alternative approach involves programming input at a lower level.
    You can use INT 21 AH=7, which allows redirection but doesn't echo
    the ^C (or any other character, for that matter); or use INT 16 AH=0
    or 10; or hook INT 9 to discard Ctrl-C and Ctrl-Break before the
    regular BIOS keyboard handler sees them; etc., etc.

    You should be aware that Ctrl-C and Ctrl-Break are processed quite
    differently internally.  Ctrl-Break, like all keystrokes, is
    processed by the BIOS code at INT 9 as soon as the user presses the
    keys, even if earlier keys are still in the keyboard buffer:  by
    default the handler at INT 1B is called.  Ctrl-C is not special to
    the BIOS, nor is it special to DOS functions 6 and 7; it _is_
    special to DOS functions 1 and 8 when at the head of the keyboard
    buffer.  You will need to make sure BREAK is OFF to prevent DOS
    polling the keyboard for Ctrl-C during non-keyboard operations.

    Some good general references are {Advanced MS-DOS} by Ray Duncan,
    ISBN 1-55615-157-8; {8088 Assembler Language Programming:  The IBM
    PC}, ISBN 0-672-22024-5, by Willen & Krantz; and {COMPUTE!'s Mapping
    the IBM PC}, ISBN 0-942386-92-2.

------------------------------

Subject: <q:4.04> - How can I disable the print screen function?

    There are really two print screen functions:  1) print current
    screen snapshot, triggered by PrintScreen or Shift-PrtSc or Shift-
    grey*, and 2) turn on continuous screen echo, started and stopped by
    Ctrl-P or Ctrl-PrtSc.

    1) Screen snapshot to printer

    The BIOS uses INT 5 for this.  Fortunately, you don't need to mess
    with that interrupt handler.  The standard handler, in BIOS versions
    dated December 1982 or later, uses a byte at 0040:0100 (= 0000:0500)
    to determine whether a print screen is currently in progress.  If it
    is, pressing PrintScreen again is ignored.  So to disable the screen
    snapshot, all you have to do is write a 1 to that byte.  When the
    user presses PrintScreen, the BIOS will think that a print screen is
    already in progress and will ignore the user's keypress.  You can re-
    enable PrintScreen by zeroing the same byte.

    Here's some simple code:

        void prtsc_allow(int allow) /* 0=disable, nonzero=enable */ {
            unsigned char far* flag = (unsigned char far*)0x00400100UL;
            *flag = (unsigned char)!allow;
        }

    2) Continuous echo of screen to printer

    If ANSI.SYS is loaded, you can easily disable the continuous echo of
    screen to printer (Ctrl-P or Ctrl-PrtSc).  Just redefine the keys by
    "printing" strings like these to the screen (BASIC print, C
    printf(), Pascal Write statements, or ECHO command in batch files),
    where <27> stands for the Escape character, ASCII 27:

        <27>[0;114;"Ctrl-PrtSc disabled"p
        <27>[16;"^P"p

    If you haven't installed ANSI.SYS, I can't offer an easy way to
    disable the echo-screen-to-printer function.

    Actually, you might not need to disable Ctrl-P and Ctrl-PrtSc.  If
    your only concern is not locking up your machine, when you see the
    "Abort, Retry, Ignore, Fail" prompt just press Ctrl-P again and then
    press I.  As an alternative, install one of the many print spoolers
    that intercept printer-status queries and always return "Printer
    ready".

------------------------------

Subject: <q:4.05> - How can my program turn NumLock (CapsLock, ScrollLock)
        on or off?

    First, if you just don't want NumLock turned on when you reboot,
    check your system's setups.  (Use Ctrl-Alt-Enter any time, or press
    a special key like Del at boot time, or run the setup program
    supplied with your system.)  Many systems now have an option in
    setup to turn NumLock off at boot time.

    You need to twiddle bit 5, 6, or 4 of location 0040:0017.  Here's
    some code:  lck() turns on a lock state, and unlck() turns it off.
    (The status lights on some keyboards may not reflect the change.  If
    yours is one, call INT 16 AH=2, "get shift status", and that may
    update them.  It will certainly do no harm.)

        #define NUM_LOCK  (1 << 5)
        #define CAPS_LOCK (1 << 6)
        #define SCRL_LOCK (1 << 4)
        void lck(int shiftype) {
            char far* kbdstatus = (char far*)0x00400017UL;
            *kbdstatus |= (char)shiftype;
        }
        void unlck(int shiftype) {
            char far* kbdstatus = (char far*)0x00400017UL;
            *kbdstatus &= ~(char)shiftype;
        }

------------------------------

Subject: <q:4.06> - How can I speed up the keyboard's auto-repeat?

    The keyboard speed has two components: delay (before a key that you
    hold down starts repeating) and typematic rate (the speed once the
    key starts repeating).  Most BIOS versions since 1986 let software
    change the delay and typematic rate by calling INT 16 AH=3, "set
    typematic rate and delay"; see Ralf Brown's interrupt list (Q 1.17).
    If you have DOS 4.0 or later, you can use the MODE CON command that
    you'll find in your DOS manual.

    On 83-key keyboards (mostly XTs), the delay and typematic rate can't
    easily be changed.  According to PC Magazine 15 Jan 1991 (x:1) page
    409, to adjust the typematic rate you need "a memory-resident
    program which simply '[watches]' the keyboard to see if you're
    holding down a key ... and after a certain time [starts] stuffing
    extra copies of the held-down key into the buffer."  No source code
    is given in that issue; but the QUICKEYS utility that PC Magazine
    published in 1986 does this sort of watching (not verified); source
    and object code are downloadable in

    <ftp://oak.oakland.edu/pub/msdos/pcmag/vol5n05.zip>

------------------------------

Subject: <q:4.07> - What is the SysRq key for?

    There is no standard use for the key.  The BIOS keyboard routines in
    INT 16 simply ignore it; therefore so do the DOS input routines in
    INT 21 as well as the keyboard routines in libraries supplied with
    high-level languages.

    When you press or release a key, the keyboard triggers hardware line
    IRQ1, and the CPU calls INT 9.  INT 9 reads the scan code from the
    keyboard and the shift states from the BIOS data area.

    What happens next depends on whether your PC's BIOS supports an
    enhanced keyboard (101 or 102 keys).  If so, INT 9 calls INT 15
    AH=4F to translate the scan code.  If the translated scan code is 54
    hex (for the SysRq key) then INT 9 calls INT 15 AH=85 and doesn't
    put the keystroke into the keyboard buffer.  The default handler of
    that function does nothing and simply returns.  (If your PC has an
    older BIOS that doesn't support the extended keyboards, INT 15 AH=4F
    is not called.  Early ATs have 84-key keyboards, so their BIOS calls
    INT 15 AH=85 but not 4F.)

    Thus your program is free to use SysRq for its own purposes, but at
    the cost of some programming.  You could hook INT 9, but it's
    probably easier to hook INT 15 AH=85, which is called when SysRq is
    pressed or released.

------------------------------

Subject: <q:4.08> - How can my program tell what kind of keyboard is on
        the system?

    Ralf Brown's Interrupt List <q:2.03> includes MEMORY.LST, a detailed
    breakdown by Robin Walker of the contents of the BIOS system block
    that starts at 0040:0000.  Bit 4 of byte 0040:0096 is "1=enhanced
    keyboard installed".  C code to test the keyboard type:

        char far *kbd_stat_byte3 = (char far *)0x00400096UL;
        if (0x10 & *kbd_stat_byte3)
            /* 101- or 102-key keyboard is installed */

    PC Magazine 15 Jan 1991 (x:1) suggests on page 412 that "for some
    clones [the above test] is not foolproof".  If you use this method
    in your program you should provide the user some way to override
    this test, or at least some way to tell your program to assume a non-
    enhanced keyboard.  The article suggests a different approach to
    determining the type of keyboard.

------------------------------

Subject: <q:4.09> - How can I tell if input, output, or stderr has
        been redirected?
Date: Tue, 7 Mar 95 12:00:00 CDT


    Normally, input and output are associated with the console (i.e.,
    with the keyboard and the screen, respectively).  If either is not,
    you know that it has been redirected.  Some source code to check
    this is available at the usual archive sites.

    If you program in Turbo Pascal, you'll want this downloadable
    collection of Turbo Pascal units:

    <ftp://garbo.uwasa.fi/pc/ts/tspa33*.zip>
    <ftp://oak.oakland.edu/pub/msdos/turbopas/tspa33*.zip>

    (where the * is 70, 60, 55, 50, or 40 for Turbo Pascal 7.0, 6.0,
    5.5, 5.0, or 4.0 respectively.)  Source code is not included.  Also
    see the downloadable Frequently Asked Questions files by Timo Salmi:

    <ftp://garbo.uwasa.fi/pc/ts/tsfaqp*.zip>
    <ftp://oak.oakland.edu/pub/msdos/info/tsfaqp*.zip>

    If you program in C, use isatty() if your implementation has it.
    Otherwise,

    <ftp://oak.oakland.edu/pub/msdos/sysutil/is_con10.zip>

    is downloadable from SimTel; it includes source code.

    Good references for the principles are PC Magazine 16 Apr 1991 (x:7)
    page 374; Ray Duncan's {Advanced MS-DOS}, ISBN 1-55615-157-8, or
    Ralf Brown's interrupt list (<q:2.03>) for INT 21 AX=4400; and Terry
    Dettman and Jim Kyle's {DOS Programmer's Reference: 2d edition},
    ISBN 0-88022-458-4, pages 602-603.

------------------------------

Subject: <q:4.10> - How can I increase the size of the keyboard buffer?
Date: Fri, 07 Jul 95 15:34:00 CDT


    Microsoft has its own keyboard extender availible on the MS-DOS
    supplmental disks for MS-DOS 6.22.

    <ftp://ftp.microsoft.com/peropsys/msdos/public/supplmnt/sup622.exe>

    I tested only one of the many available device drivers that do this,
    namely BUF160, which extends the keyboard buffer to 160 characters.
    It performed flawlessly for two years with MS-DOS 5 and Windows 3.1.
    It's downloadable as

    <ftp://oak.oakland.edu/pub/msdos/keyboard/buf160_6.zip>
    <ftp://garbo.uwasa.fi/pc/keyboard/buf160_6.zip>

------------------------------

Subject: <q:4.11> - How can I stuff characters into the keyboard buffer?

    If your computer has an enhanced keyboard (see <q:4.08> - "How can my
    program tell what kind of keyboard is on the system?"), put the scan
    code in CH and the ASCII character in CL, then execute INT 16 AH=5.
    The return in AL is 0 for success or 1 for buffer full.

------------------------------

Subject: End

(End of comp.os.msdos.programmer FAQ Version 2.06 Part 2/5)
(This text is copyright 1996 by Jeffrey Carlyle. All rights reserved.)


// Jeffrey Carlyle, Stratoware, Bowling Green, KY USA _,,-^`--.
// comp.os.msdos.programmer FAQ maintainer      .__,-'         \
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