--- /dev/null
+@c This is part of the Emacs manual.
+@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997 Free Software Foundation, Inc.
+@c See file emacs.texi for copying conditions.
+@node MS-DOS, Manifesto, Antinews, Top
+@appendix Emacs and MS-DOS
+@cindex MS-DOG
+@cindex MS-DOS peculiarities
+
+ This section briefly describes the peculiarities of using Emacs under
+the MS-DOS ``operating system'' (also known as ``MS-DOG''). If you
+build Emacs for MS-DOS, the binary will also run on Windows 3.X, Windows
+NT, Windows 9X, or OS/2 as a DOS application; the information in this
+chapter applies for all of those systems, if you use an Emacs that was
+built for MS-DOS.
+
+ Note that it is possible to build Emacs specifically for Windows NT or
+Windows 9X. If you do that, most of this chapter does not apply;
+instead, you get behavior much closer to what is documented in the rest
+of the manual, including support for long file names, multiple frames,
+scroll bars, mouse menus, and subprocesses. However, the section on
+text files and binary files does still apply. There are also two
+sections at the end of this chapter which apply specifically for Windows
+NT and 9X.
+
+@menu
+* Input: MS-DOS Input. Keyboard and mouse usage on MS-DOS.
+* Display: MS-DOS Display. Fonts, frames and display size on MS-DOS.
+* Files: MS-DOS File Names. File name conventions on MS-DOS.
+* Text and Binary:: Text files on MS-DOS use CRLF to separate lines.
+* Printing: MS-DOS Printing. How to specify the printer on MS-DOS.
+* I18N: MS-DOS and MULE. Support for internationalization on MS-DOS.
+* Processes: MS-DOS Processes. Running subprocesses on MS-DOS.
+* Windows Processes:: Running subprocesses on Windows.
+* Windows System Menu:: Controlling what the ALT key does.
+@end menu
+
+@node MS-DOS Input
+@section Keyboard and Mouse on MS-DOS
+
+@cindex Meta (under MS-DOS)
+@cindex Hyper (under MS-DOS)
+@cindex Super (under MS-DOS)
+@vindex dos-super-key
+@vindex dos-hyper-key
+ The PC keyboard maps use the left @key{ALT} key as the @key{META} key.
+You have two choices for emulating the @key{SUPER} and @key{HYPER} keys:
+choose either the right @key{CTRL} key or the right @key{ALT} key by
+setting the variables @code{dos-hyper-key} and @code{dos-super-key} to 1
+or 2 respectively. If neither @code{dos-super-key} nor
+@code{dos-hyper-key} is 1, then by default the right @key{ALT} key is
+also mapped to the @key{META} key. However, if the MS-DOS international
+keyboard support program @file{KEYB.COM} is installed, Emacs will
+@emph{not} map the right @key{ALT} to @key{META}, since it is used for
+accessing characters like @kbd{~} and @kbd{@@} on non-US keyboard
+layouts; in this case, you may only use the left @key{ALT} as @key{META}
+key.
+
+@kindex C-j @r{(MS-DOS)}
+@vindex dos-keypad-mode
+ The variable @code{dos-keypad-mode} is a flag variable that controls
+what key codes are returned by keys in the numeric keypad. You can also
+define the keypad @key{ENTER} key to act like @kbd{C-j}, by putting the
+following line into your @file{_emacs} file:
+
+@smallexample
+;; Make the Enter key from the Numeric keypad act as C-j.
+(define-key function-key-map [kp-enter] [?\C-j])
+@end smallexample
+
+@kindex DEL @r{(MS-DOS)}
+@kindex BS @r{(MS-DOS)}
+ The key that is called @key{DEL} in Emacs (because that's how it is
+designated on most workstations) is known as @key{BS} (backspace) on a
+PC. That is why the PC-specific terminal initialization remaps the
+@key{BS} key to act as @key{DEL}; the @key{DEL} key is remapped to act
+as @kbd{C-d} for the same reasons.
+
+@kindex C-g @r{(MS-DOS)}
+@kindex C-BREAK @r{(MS-DOS)}
+@cindex quitting on MS-DOS
+ Emacs built for MS-DOS recognizes @kbd{C-@key{BREAK}} as a quit
+character, just like @kbd{C-g}. This is because Emacs cannot detect
+that you have typed @kbd{C-g} until it is ready for more input. As a
+consequence, you cannot use @kbd{C-g} to stop a running command
+(@pxref{Quitting}). By contrast, @kbd{C-@key{BREAK}} @emph{is} detected
+as soon as you type it (as @kbd{C-g} is on other systems), so it can be
+used to stop a running command and for emergency escape
+(@pxref{Emergency Escape}).
+
+@cindex mouse support under MS-DOS
+ Emacs on MS-DOS supports a mouse (on the default terminal only).
+The mouse commands work as documented, including those that use menus
+and the menu bar (@pxref{Menu Bar}). Scroll bars don't work in
+MS-DOS Emacs. PC mice usually have only two buttons; these act as
+@kbd{Mouse-1} and @kbd{Mouse-2}, but if you press both of them
+together, that has the effect of @kbd{Mouse-3}.
+
+@cindex Windows clipboard support
+ Emacs built for MS-DOS supports clipboard operations when it runs on
+Windows. Commands that put text on the kill ring, or yank text from the
+ring, check the Windows clipboard first, just as Emacs does on X Windows
+(@pxref{Mouse Commands}). Only the primary selection and the cut buffer
+are supported by MS-DOS Emacs on Windows; the secondary selection always
+appears as empty.
+
+ Due to the way clipboard access is implemented by Windows, the
+length of text you can put into the clipboard is limited by the amount
+of free DOS memory that is available to Emacs. Usually, up to 620KB of
+text can be put into the clipboard, but this limit depends on the system
+configuration and is lower if you run Emacs as a subprocess of
+another program. If the killed text does not fit, Emacs prints a
+message saying so, and does not put the text into the clipboard.
+
+ Null characters also cannot be put into the Windows clipboard. If the
+killed text includes null characters, Emacs does not put such text into
+the clipboard, and prints in the echo area a message to that effect.
+
+@vindex dos-display-scancodes
+ The variable @code{dos-display-scancodes}, when non-@code{nil},
+directs Emacs to display the ASCII value and the keyboard scan code of
+each keystroke; this feature serves as a complement to the
+@code{view-lossage} command, for debugging.
+
+@node MS-DOS Display
+@section Display on MS-DOS
+@cindex faces under MS-DOS
+@cindex fonts, emulating under MS-DOS
+
+ Display on MS-DOS cannot use font variants, like bold or italic,
+but it does support
+multiple faces, each of which can specify a foreground and a background
+color. Therefore, you can get the full functionality of Emacs packages
+that use fonts (such as @code{font-lock}, Enriched Text mode, and
+others) by defining the relevant faces to use different colors. Use the
+@code{list-colors-display} command (@pxref{Frame Parameters}) and the
+@code{list-faces-display} command (@pxref{Faces}) to see what colors and
+faces are available and what they look like.
+
+ The section @ref{MS-DOS and MULE}, later in this chapter, describes
+how Emacs displays glyphs and characters which aren't supported by the
+native font built into the DOS display.
+
+@cindex frames on MS-DOS
+ Multiple frames (@pxref{Frames}) are supported on MS-DOS, but they all
+overlap, so you only see a single frame at any given moment. That
+single visible frame occupies the entire screen. When you run Emacs
+from MS-Windows DOS box, you can make the visible frame smaller than
+the full screen, but Emacs still cannot display more than a single
+frame at a time.
+
+@cindex frame size under MS-DOS
+@findex mode4350
+@findex mode25
+ The @code{mode4350} command switches the display to 43 or 50
+lines, depending on your hardware; the @code{mode25} command switches
+to the default 80x25 screen size.
+
+ By default, Emacs only knows how to set screen sizes of 80 columns by
+25, 28, 35, 40, 43 or 50 rows. However, if your video adapter has
+special video modes that will switch the display to other sizes, you can
+have Emacs support those too. When you ask Emacs to switch the frame to
+@var{n} rows by @var{m} columns dimensions, it checks if there is a
+variable called @code{screen-dimensions-@var{n}x@var{m}}, and if so,
+uses its value (which must be an integer) as the video mode to switch
+to. (Emacs switches to that video mode by calling the BIOS @code{Set
+Video Mode} function with the value of
+@code{screen-dimensions-@var{n}x@var{m}} in the @code{AL} register.)
+For example, suppose your adapter will switch to 66x80 dimensions when
+put into video mode 85. Then you can make Emacs support this screen
+size by putting the following into your @file{_emacs} file:
+
+@example
+(setq screen-dimensions-66x80 85)
+@end example
+
+ Since Emacs on MS-DOS can only set the frame size to specific
+supported dimensions, it cannot honor every possible frame resizing
+request. When an unsupported size is requested, Emacs chooses the next
+larger supported size beyond the specified size. For example, if you
+ask for 36x80 frame, you will get 40x80 instead.
+
+ The variables @code{screen-dimensions-@var{n}x@var{m}} are used only
+when they exactly match the specified size; the search for the next
+larger supported size ignores them. In the above example, even if your
+VGA supports 38x80 dimensions and you define a variable
+@code{screen-dimensions-38x80} with a suitable value, you will still get
+40x80 screen when you ask for a 36x80 frame. If you want to get the
+38x80 size in this case, you can do it by setting the variable named
+@code{screen-dimensions-36x80} with the same video mode value as
+@code{screen-dimensions-38x80}.
+
+ Changing frame dimensions on MS-DOS has the effect of changing all the
+other frames to the new dimensions.
+
+@node MS-DOS File Names
+@section File Names on MS-DOS
+@cindex file names under MS-DOS
+@cindex init file, default name under MS-DOS
+
+ MS-DOS normally uses a backslash, @samp{\}, to separate name units
+within a file name, instead of the slash used on other systems. Emacs
+on MS-DOS permits use of either slash or backslash, and also knows
+about drive letters in file names.
+
+ On MS-DOS, file names are case-insensitive and limited to eight
+characters, plus optionally a period and three more characters. Emacs
+knows enough about these limitations to handle file names that were
+meant for other operating systems. For instance, leading dots @samp{.}
+in file names are invalid in MS-DOS, so Emacs transparently converts
+them to underscores @samp{_}; thus your default init file (@pxref{Init
+File}) is called @file{_emacs} on MS-DOS. Excess characters before or
+after the period are generally ignored by MS-DOS itself; thus, if you
+visit the file @file{LongFileName.EvenLongerExtension}, you will
+silently get @file{longfile.eve}, but Emacs will still display the long
+file name on the mode line. Other than that, it's up to you to specify
+file names which are valid under MS-DOS; the transparent conversion as
+described above only works on file names built into Emacs.
+
+@cindex backup file names on MS-DOS
+ The above restrictions on the file names on MS-DOS make it almost
+impossible to construct the name of a backup file (@pxref{Backup
+Names}) without losing some of the original file name characters. For
+example, the name of a backup file for @file{docs.txt} is
+@file{docs.tx~} even if single backup is used.
+
+@cindex file names under Windows 95/NT
+@cindex long file names in DOS box under Windows 95/NT
+ If you run Emacs as a DOS application under Windows 9X, you can
+turn on support for long file names. If you do that, Emacs doesn't
+truncate file names or convert them to lower case; instead, it uses the
+file names that you specify, verbatim. To enable long file name
+support, set the environment variable @code{LFN} to @samp{y} before
+starting Emacs. Unfortunately, Windows NT doesn't allow DOS programs to
+access long file names, so Emacs built for MS-DOS will only see their
+short 8+3 aliases.
+
+@cindex @code{HOME} directory under MS-DOS
+ MS-DOS has no notion of home directory, so Emacs on MS-DOS pretends
+that the directory where it is installed is the value of @code{HOME}
+environment variable. That is, if your Emacs binary,
+@file{emacs.exe}, is in the directory @file{c:/utils/emacs/bin}, then
+Emacs acts as if @code{HOME} were set to @samp{c:/utils/emacs}. In
+particular, that is where Emacs looks for the init file @file{_emacs}.
+With this in mind, you can use @samp{~} in file names as an alias for
+the home directory, as you would in Unix. You can also set @code{HOME}
+variable in the environment before starting Emacs; its value will then
+override the above default behavior.
+
+ Emacs on MS-DOS handles the directory name @file{/dev} specially,
+because of a feature in the emulator libraries of DJGPP that pretends
+I/O devices have names in that directory. We recommend that you avoid
+using an actual directory named @file{/dev} on any disk.
+
+@node Text and Binary
+@section Text Files and Binary Files
+@cindex text and binary files on MS-DOS/MS-Windows
+
+ GNU Emacs uses newline characters to separate text lines. This is the
+convention used on Unix, on which GNU Emacs was developed, and on GNU
+systems since they are modeled on Unix.
+
+@cindex end-of-line conversion on MS-DOS/MS-Windows
+ MS-DOS and MS-Windows normally use carriage-return linefeed, a
+two-character sequence, to separate text lines. (Linefeed is the same
+character as newline.) Therefore, convenient editing of typical files
+with Emacs requires conversion of these end-of-line (EOL) sequences.
+And that is what Emacs normally does: it converts carriage-return
+linefeed into newline when reading files, and converts newline into
+carriage-return linefeed when writing files. The same mechanism that
+handles conversion of international character codes does this conversion
+also (@pxref{Coding Systems}).
+
+@cindex cursor location, under MS-DOS
+@cindex point location, under MS-DOS
+ One consequence of this special format-conversion of most files is
+that character positions as reported by Emacs (@pxref{Position Info}) do
+not agree with the file size information known to the operating system.
+
+@vindex file-name-buffer-file-type-alist
+ Some kinds of files should not be converted, because their contents
+are not really text. Therefore, Emacs on MS-DOS distinguishes certain
+files as @dfn{binary files}, and reads and writes them verbatim. (This
+distinction is not part of MS-DOS; it is made by Emacs only.) These
+include executable programs, compressed archives, etc. Emacs uses the
+file name to decide whether to treat a file as binary: the variable
+@code{file-name-buffer-file-type-alist} defines the file-name patterns
+that indicate binary files. Note that if a file name matches one of the
+patterns for binary files in @code{file-name-buffer-file-type-alist},
+Emacs uses the @code{no-conversion} coding system (@pxref{Coding
+Systems}) which turns off @emph{all} coding-system conversions, not only
+the EOL conversion.
+
+ In addition, if Emacs recognizes from a file's contents that it uses
+newline rather than carriage-return linefeed as its line separator, it
+does not perform conversion when reading or writing that file. Thus,
+you can read and edit files from Unix or GNU systems on MS-DOS with no
+special effort, and they will be left with their Unix-style EOLs.
+
+@findex find-file-text
+@findex find-file-binary
+ You can visit a file and specify whether to treat a file as text or
+binary using the commands @code{find-file-text} and
+@code{find-file-binary}. End-of-line conversion is part of the general
+coding system conversion mechanism, so another way to control whether to
+treat a file as text or binary is with the commands for specifying a
+coding system (@pxref{Specify Coding}). For example,
+@kbd{C-x @key{RET} c undecided-unix @key{RET} C-x C-f foobar.txt}
+visits the file @file{foobar.txt} without converting the EOLs.
+
+ The mode line indicates whether end-of-line translation was used for
+the current buffer. Normally a colon appears after the coding system
+letter near the beginning of the mode line. If MS-DOS end-of-line
+translation is in use for the buffer, this character changes to a
+backslash.
+
+@cindex untranslated file system
+@findex add-untranslated-filesystem
+ When you use NFS or Samba to access file systems that reside on
+computers using Unix or GNU systems, Emacs should not perform
+end-of-line translation on any files in these file systems--not even
+when you create a new file. To request this, designate these file
+systems as @dfn{untranslated} file systems by calling the function
+@code{add-untranslated-filesystem}. It takes one argument: the file
+system name, including a drive letter and optionally a directory. For
+example,
+
+@example
+(add-untranslated-filesystem "Z:")
+@end example
+
+@noindent
+designates drive Z as an untranslated file system, and
+
+@example
+(add-untranslated-filesystem "Z:\\foo")
+@end example
+
+@noindent
+designates directory @file{\foo} on drive Z as an untranslated file
+system.
+
+ Most often you would use @code{add-untranslated-filesystem} in your
+@file{_emacs} file, or in @file{site-start.el} so that all the users at
+your site get the benefit of it.
+
+@findex remove-untranslated-filesystem
+ To countermand the effect of @code{add-untranslated-filesystem}, use
+the function @code{remove-untranslated-filesystem}. This function takes
+one argument, which should be a string just like the one that was used
+previously with @code{add-untranslated-filesystem}.
+
+@node MS-DOS Printing
+@section Printing and MS-DOS
+
+ Printing commands, such as @code{lpr-buffer} (@pxref{Hardcopy}) and
+@code{ps-print-buffer} (@pxref{Postscript}) can work in MS-DOS by
+sending the output to one of the printer ports, if a Unix-style @code{lpr}
+program is unavailable. A few DOS-specific variables control how this
+works.
+
+@vindex dos-printer
+ If you want to use your local printer, printing on it in the usual DOS
+manner, then set the Lisp variable @code{dos-printer} to the name of the
+printer port---for example, @code{"PRN"}, the usual local printer port
+(that's the default), or @code{"LPT2"} or @code{"COM1"} for a serial
+printer. You can also set @code{dos-printer} to a file name, in which
+case ``printed'' output is actually appended to that file. If you set
+@code{dos-printer} to @code{"NUL"}, printed output is silently
+discarded (sent to the system null device).
+
+ If you set @code{dos-printer} to a file name, it's best to use an
+absolute file name. Emacs changes the working directory according to
+the default directory of the current buffer, so if the file name in
+@code{dos-printer} is relative, you will end up with several such files,
+each one in the directory of the buffer from which the printing was
+done.
+
+@findex print-buffer @r{(MS-DOS)}
+@findex print-region @r{(MS-DOS)}
+@vindex lpr-headers-switches @r{(MS-DOS)}
+ The commands @code{print-buffer} and @code{print-region} call the
+@code{pr} program, or use special switches to the @code{lpr} program, to
+produce headers on each printed page. MS-DOS doesn't normally have
+these programs, so by default, the variable @code{lpr-headers-switches}
+is set so that the requests to print page headers are silently ignored.
+Thus, @code{print-buffer} and @code{print-region} produce the same
+output as @code{lpr-buffer} and @code{lpr-region}, respectively. If you
+do have a suitable @code{pr} program (for example, from GNU Textutils),
+set @code{lpr-headers-switches} to @code{nil}; Emacs will then call
+@code{pr} to produce the page headers, and print the resulting output as
+specified by @code{dos-printer}.
+
+@vindex print-region-function @r{(MS-DOS)}
+@cindex lpr usage under MS-DOS
+@vindex lpr-command @r{(MS-DOS)}
+@vindex lpr-switches @r{(MS-DOS)}
+ Finally, if you do have an @code{lpr} work-alike, you can set
+@code{print-region-function} to @code{nil}. Then Emacs uses @code{lpr}
+for printing, as on other systems. (If the name of the program isn't
+@code{lpr}, set the @code{lpr-command} variable to specify where to find
+it.)
+
+@findex ps-print-buffer @r{(MS-DOS)}
+@findex ps-spool-buffer @r{(MS-DOS)}
+@vindex dos-ps-printer
+@vindex ps-lpr-command @r{(MS-DOS)}
+@vindex ps-lpr-switches @r{(MS-DOS)}
+ A separate variable, @code{dos-ps-printer}, defines how PostScript
+files should be printed. If its value is a string, it is used as the
+name of the device (or file) to which PostScript output is sent, just as
+@code{dos-printer} is used for non-PostScript printing. (These are two
+distinct variables in case you have two printers attached to two
+different ports, and only one of them is a PostScript printer.) If the
+value of @code{dos-ps-printer} is not a string, then the variables
+@code{ps-lpr-command} and @code{ps-lpr-switches} (@pxref{Postscript})
+control how to print PostScript files. Thus, if you have a
+non-PostScript printer, you can set these variables to the name and the
+switches appropriate for a PostScript interpreter program (such as
+Ghostscript).
+
+ For example, to use Ghostscript for printing on an Epson printer
+connected to @samp{LPT2} port, put this on your @file{.emacs} file:
+
+@example
+(setq dos-ps-printer t) ; @r{Anything but a string.}
+(setq ps-lpr-command "c:/gs/gs386")
+(setq ps-lpr-switches '("-q" "-dNOPAUSE"
+ "-sDEVICE=epson"
+ "-r240x72"
+ "-sOutputFile=LPT2"
+ "-Ic:/gs"
+ "-"))
+@end example
+
+@noindent
+(This assumes that Ghostscript is installed in the @file{"c:/gs"}
+directory.)
+
+@node MS-DOS and MULE
+@section International Support on MS-DOS
+@cindex international support @r{(MS-DOS)}
+
+ Emacs on MS-DOS supports the same international character sets as it
+does on Unix and other platforms (@pxref{International}), including
+coding systems for converting between the different character sets.
+However, due to incompatibilities between MS-DOS/MS-Windows and Unix,
+there are several DOS-specific aspects of this support that users should
+be aware of. This section describes these aspects.
+
+@table @kbd
+@item M-x dos-codepage-setup
+Set up Emacs display and coding systems as appropriate for the current
+DOS codepage.
+
+@item M-x codepage-setup
+Create a coding system for a certain DOS codepage.
+@end table
+
+@cindex codepage, MS-DOS
+@cindex DOS codepages
+ MS-DOS is designed to support one character set of 256 characters at
+any given time, but gives you a variety of character sets to choose
+from. The alternative character sets are known as @dfn{DOS codepages}.
+Each codepage includes all 128 ASCII characters, but the other 128
+characters (codes 128 through 255) vary from one codepage to another.
+Each DOS codepage is identified by a 3-digit number, such as 850, 862,
+etc.
+
+ In contrast to X Windows, which lets you use several fonts at the same
+time, MS-DOS doesn't allow use of several codepages in a single session.
+Instead, MS-DOS loads a single codepage at system startup, and you must
+reboot MS-DOS to change it@footnote{Normally, one particular codepage is
+burnt into the display memory, while other codepages can be installed by
+modifying system configuration files, such as @file{CONFIG.SYS}, and
+rebooting.}. Much the same limitation applies when you run DOS
+executables on other systems such as MS-Windows.
+
+@cindex unibyte operation @r{(MS-DOS)}
+ If you invoke Emacs on MS-DOS with the @samp{--unibyte} option
+(@pxref{Initial Options}), Emacs does not perform any conversion of
+non-ASCII characters. Instead, it reads and writes any non-ASCII
+characters verbatim, and sends their 8-bit codes to the display
+verbatim. Thus, unibyte Emacs on MS-DOS supports the current codepage,
+whatever it may be, but cannot even represent any other characters.
+
+@vindex dos-codepage
+ For multibyte operation on MS-DOS, Emacs needs to know which
+characters the chosen DOS codepage can display. So it queries the
+system shortly after startup to get the chosen codepage number, and
+stores the number in the variable @code{dos-codepage}. Some systems
+return the default value 437 for the current codepage, even though the
+actual codepage is different. (This typically happens when you use the
+codepage built into the display hardware.) You can specify a different
+codepage for Emacs to use by setting the variable @code{dos-codepage} in
+your init file.
+
+@cindex language environment, automatic selection on @r{MS-DOS}
+ Multibyte Emacs supports only certain DOS codepages, those that encode
+a single ISO 8859 character set, and it knows which ISO character set
+based on the codepage number. Emacs automatically creates a coding
+system to support reading and writing files that use the current
+codepage, and uses this coding system by default. The name of this
+coding system is @code{cp@var{nnn}}, where @var{nnn} is the codepage
+number.@footnote{The standard Emacs coding systems for ISO 8859 are not
+quite right for the purpose, because typically the DOS codepage does not
+match the standard ISO character codes. For example, the
+letter @samp{@,{c}} (@samp{c} with cedilla) has code 231 in the standard
+Latin-1 character set, but the corresponding DOS codepage 850 uses code
+135 for this glyph.}
+
+@cindex mode line @r{(MS-DOS)}
+ All the @code{cp@var{nnn}} coding systems use the letter @samp{D} (for
+``DOS'') as their mode-line mnemonic. Since both the terminal coding
+system and the default coding system for file I/O are set to the proper
+@code{cp@var{nnn}} coding system at startup, it is normal for the mode
+line on MS-DOS to begin with @samp{-DD\-}. @xref{Mode Line}.
+
+ Since the codepage number also indicates which script you are using,
+Emacs automatically runs @code{set-language-environment} to select the
+language environment for that script (@pxref{Language Environments}).
+
+ If a buffer contains a character belonging to some other ISO 8859
+character set, not the one that the chosen DOS codepage supports, Emacs
+displays it using a sequence of ASCII characters. For example, if the
+current codepage doesn't have a glyph for the letter @samp{@`o} (small
+@samp{o} with a grave accent), it is displayed as @samp{@{`o@}}, where
+the braces serve as a visual indication that this is a single character.
+(This may look awkward for some non-Latin characters, such as those from
+Greek or Hebrew alphabets, but it is still readable by a person who
+knows the language.) Even though the character may occupy several
+columns on the screen, it is really still just a single character, and
+all Emacs commands treat it as one.
+
+@vindex dos-unsupported-character-glyph
+ Not all characters in DOS codepages correspond to ISO 8859
+characters---some are used for other purposes, such as box-drawing
+characters and other graphics. Emacs cannot represent these characters
+internally, so when you read a file that uses these characters, they are
+converted into a particular character code, specified by the variable
+@code{dos-unsupported-character-glyph}.
+
+ Emacs supports many other characters sets aside from ISO 8859, but it
+cannot display them on MS-DOS. So if one of these multibyte characters
+appears in a buffer, Emacs on MS-DOS displays a solid box instead of the
+character.
+
+@findex codepage-setup
+ By default, Emacs defines a coding system to support the current
+codepage. To define a coding system for some other codepage (e.g., to
+visit a file written on a DOS machine in another country), use the
+@kbd{M-x codepage-setup} command. It prompts for the 3-digit code of
+the codepage, with completion, then creates the coding system for the
+specified codepage. You can then use the new coding system to read and
+write files, but you must specify it explicitly for the file command
+when you want to use it (@pxref{Specify Coding}).
+
+ These coding systems are also useful for visiting a file encoded using
+a DOS codepage, using Emacs running on some other operating system.
+
+@node MS-DOS Processes
+@section Subprocesses on MS-DOS
+
+@cindex compilation under MS-DOS
+@cindex inferior processes under MS-DOS
+@findex compile @r{(MS-DOS)}
+@findex grep @r{(MS-DOS)}
+ Because MS-DOS is a single-process ``operating system,''
+asynchronous subprocesses are not available. In particular, Shell
+mode and its variants do not work. Most Emacs features that use
+asynchronous subprocesses also don't work on MS-DOS, including
+spelling correction and GUD. When in doubt, try and see; commands that
+don't work print an error message saying that asynchronous processes
+aren't supported.
+
+ Compilation under Emacs with @kbd{M-x compile}, searching files with
+@kbd{M-x grep} and displaying differences between files with @kbd{M-x
+diff} do work, by running the inferior processes synchronously. This
+means you cannot do any more editing until the inferior process
+finishes.
+
+ By contrast, Emacs compiled as native Windows application
+@strong{does} support asynchronous subprocesses. @xref{Windows
+Processes}.
+
+@cindex printing under MS-DOS
+ Printing commands, such as @code{lpr-buffer} (@pxref{Hardcopy}) and
+@code{ps-print-buffer} (@pxref{Postscript}), work in MS-DOS by sending
+the output to one of the printer ports. @xref{MS-DOS Printing}.
+
+ When you run a subprocess synchronously on MS-DOS, make sure the
+program terminates and does not try to read keyboard input. If the
+program does not terminate on its own, you will be unable to terminate
+it, because MS-DOS provides no general way to terminate a process.
+Pressing @kbd{C-c} or @kbd{C-@key{BREAK}} might sometimes help in these
+cases.
+
+ Accessing files on other machines is not supported on MS-DOS. Other
+network-oriented commands such as sending mail, Web browsing, remote
+login, etc., don't work either, unless network access is built into
+MS-DOS with some network redirector.
+
+@cindex directory listing on MS-DOS
+@vindex dired-listing-switches @r{(MS-DOS)}
+ Dired on MS-DOS uses the @code{ls-lisp} package where other
+platforms use the system @code{ls} command. Therefore, Dired on
+MS-DOS supports only some of the possible options you can mention in
+the @code{dired-listing-switches} variable. The options that work are
+@samp{-A}, @samp{-a}, @samp{-c}, @samp{-i}, @samp{-r}, @samp{-S},
+@samp{-s}, @samp{-t}, and @samp{-u}.
+
+@node Windows Processes
+@section Subprocesses on Windows 95 and NT
+
+Emacs compiled as a native Windows application (as opposed to the DOS
+version) includes full support for asynchronous subprocesses.
+In the Windows version, synchronous and asynchronous subprocesses work
+fine on both
+Windows 95 and Windows NT as long as you run only 32-bit Windows
+applications. However, when you run a DOS application in a subprocess,
+you may encounter problems or be unable to run the application at all;
+and if you run two DOS applications at the same time in two
+subprocesses, you may have to reboot your system.
+
+Since the standard command interpreter (and most command line utilities)
+on Windows 95 are DOS applications, these problems are significant when
+using that system. But there's nothing we can do about them; only
+Microsoft can fix them.
+
+If you run just one DOS application subprocess, the subprocess should
+work as expected as long as it is ``well-behaved'' and does not perform
+direct screen access or other unusual actions. If you have a CPU
+monitor application, your machine will appear to be 100% busy even when
+the DOS application is idle, but this is only an artifact of the way CPU
+monitors measure processor load.
+
+You must terminate the DOS application before you start any other DOS
+application in a different subprocess. Emacs is unable to interrupt or
+terminate a DOS subprocess. The only way you can terminate such a
+subprocess is by giving it a command that tells its program to exit.
+
+If you attempt to run two DOS applications at the same time in separate
+subprocesses, the second one that is started will be suspended until the
+first one finishes, even if either or both of them are asynchronous.
+
+If you can go to the first subprocess, and tell it to exit, the second
+subprocess should continue normally. However, if the second subprocess
+is synchronous, Emacs itself will be hung until the first subprocess
+finishes. If it will not finish without user input, then you have no
+choice but to reboot if you are running on Windows 95. If you are
+running on Windows NT, you can use a process viewer application to kill
+the appropriate instance of ntvdm instead (this will terminate both DOS
+subprocesses).
+
+If you have to reboot Windows 95 in this situation, do not use the
+@code{Shutdown} command on the @code{Start} menu; that usually hangs the
+system. Instead, type @kbd{CTL-ALT-@key{DEL}} and then choose
+@code{Shutdown}. That usually works, although it may take a few minutes
+to do its job.
+
+@node Windows System Menu
+@section Using the System Menu on Windows
+
+Emacs compiled as a native Windows application normally turns off the
+Windows feature that tapping the @key{ALT}
+key invokes the Windows menu. The reason is that the @key{ALT} also
+serves as @key{META} in Emacs. When using Emacs, users often press the
+@key{META} key temporarily and then change their minds; if this has the
+effect of bringing up the Windows menu, it alters the meaning of
+subsequent commands. Many users find this frustrating.
+
+@vindex w32-pass-alt-to-system
+You can reenable Windows's default handling of tapping the @key{ALT} key
+by setting @code{w32-pass-alt-to-system} to a non-@code{nil} value.
+