diff --git a/src/pty.c b/src/pty.c
new file mode 100644
index 0000000..c28d78e
--- /dev/null
+++ b/src/pty.c
@@ -0,0 +1,425 @@
+/* vi:set ts=8 sts=4 sw=4:
+ *
+ * VIM - Vi IMproved		by Bram Moolenaar
+ *
+ * Do ":help uganda"  in Vim to read copying and usage conditions.
+ * Do ":help credits" in Vim to see a list of people who contributed.
+ * See README.txt for an overview of the Vim source code.
+ */
+/*
+ * The stuff in this file mostly comes from the "screen" program.
+ * Included with permission from Juergen Weigert.
+ * Copied from "pty.c".  "putenv.c" was used for putenv() in misc2.c.
+ *
+ * It has been modified to work better with Vim.
+ * The parts that are not used in Vim have been deleted.
+ * See the "screen" sources for the complete stuff.
+ */
+
+/* Copyright (c) 1993
+ *	Juergen Weigert (jnweiger@immd4.informatik.uni-erlangen.de)
+ *	Michael Schroeder (mlschroe@immd4.informatik.uni-erlangen.de)
+ * Copyright (c) 1987 Oliver Laumann
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program (see the file COPYING); if not, write to the
+ * Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA
+ */
+
+/* RCS_ID("$Id$ FAU") */
+
+#include "vim.h"
+
+#ifdef HAVE_FCNTL_H
+# include <fcntl.h>
+#endif
+
+#include <signal.h>
+
+#ifdef __CYGWIN32__
+# include <sys/termios.h>
+#endif
+
+#if HAVE_SYS_IOCTL_H
+# include <sys/ioctl.h>
+#endif
+
+#if HAVE_STROPTS_H
+#include <sys/types.h>
+#ifdef sinix
+#define buf_T __system_buf_t__
+#endif
+#include <stropts.h>
+#ifdef sinix
+#undef buf_T
+#endif
+# ifdef sun
+#  include <sys/conf.h>
+# endif
+#endif
+
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#if HAVE_TERMIO_H
+# include <termio.h>
+#else
+# if HAVE_TERMIOS_H
+#  include <termios.h>
+# endif
+#endif
+
+#if HAVE_SYS_STREAM_H
+# include <sys/stream.h>
+#endif
+
+#if HAVE_SYS_PTEM_H
+# include <sys/ptem.h>
+#endif
+
+#if !defined(sun) && !defined(VMS) && !defined(MACOS)
+# include <sys/ioctl.h>
+#endif
+
+#if defined(sun) && defined(LOCKPTY) && !defined(TIOCEXCL)
+# include <sys/ttold.h>
+#endif
+
+#ifdef ISC
+# include <sys/tty.h>
+# include <sys/sioctl.h>
+# include <sys/pty.h>
+#endif
+
+#ifdef sgi
+# include <sys/sysmacros.h>
+#endif
+
+#if defined(_INCLUDE_HPUX_SOURCE) && !defined(hpux)
+# define hpux
+#endif
+
+/*
+ * if no PTYRANGE[01] is in the config file, we pick a default
+ */
+#ifndef PTYRANGE0
+# define PTYRANGE0 "qprs"
+#endif
+#ifndef PTYRANGE1
+# define PTYRANGE1 "0123456789abcdef"
+#endif
+
+/* SVR4 pseudo ttys don't seem to work with SCO-5 */
+#ifdef M_UNIX
+# undef HAVE_SVR4_PTYS
+#endif
+
+static void initmaster __ARGS((int));
+
+/*
+ *  Open all ptys with O_NOCTTY, just to be on the safe side
+ *  (RISCos mips breaks otherwise)
+ */
+#ifndef O_NOCTTY
+# define O_NOCTTY 0
+#endif
+
+    static void
+initmaster(f)
+    int f;
+{
+#ifndef VMS
+# ifdef POSIX
+    tcflush(f, TCIOFLUSH);
+# else
+#  ifdef TIOCFLUSH
+    (void)ioctl(f, TIOCFLUSH, (char *) 0);
+#  endif
+# endif
+# ifdef LOCKPTY
+    (void)ioctl(f, TIOCEXCL, (char *) 0);
+# endif
+#endif
+}
+
+/*
+ * This causes a hang on some systems, but is required for a properly working
+ * pty on others.  Needs to be tuned...
+ */
+    int
+SetupSlavePTY(fd)
+    int fd;
+{
+    if (fd < 0)
+	return 0;
+#if defined(I_PUSH) && defined(HAVE_SVR4_PTYS) && !defined(sgi) && !defined(linux) && !defined(__osf__) && !defined(M_UNIX)
+# if defined(HAVE_SYS_PTEM_H) || defined(hpux)
+    if (ioctl(fd, I_PUSH, "ptem") != 0)
+	return -1;
+# endif
+    if (ioctl(fd, I_PUSH, "ldterm") != 0)
+	return -1;
+# ifdef sun
+    if (ioctl(fd, I_PUSH, "ttcompat") != 0)
+	return -1;
+# endif
+#endif
+    return 0;
+}
+
+
+#if defined(OSX) && !defined(PTY_DONE)
+#define PTY_DONE
+    int
+OpenPTY(ttyn)
+    char **ttyn;
+{
+    int		f;
+    static char TtyName[32];
+
+    if ((f = open_controlling_pty(TtyName)) < 0)
+	return -1;
+    initmaster(f);
+    *ttyn = TtyName;
+    return f;
+}
+#endif
+
+#if (defined(sequent) || defined(_SEQUENT_)) && defined(HAVE_GETPSEUDOTTY) \
+	&& !defined(PTY_DONE)
+#define PTY_DONE
+    int
+OpenPTY(ttyn)
+    char **ttyn;
+{
+    char	*m, *s;
+    int		f;
+    /* used for opening a new pty-pair: */
+    static char PtyName[32];
+    static char TtyName[32];
+
+    if ((f = getpseudotty(&s, &m)) < 0)
+	return -1;
+#ifdef _SEQUENT_
+    fvhangup(s);
+#endif
+    strncpy(PtyName, m, sizeof(PtyName));
+    strncpy(TtyName, s, sizeof(TtyName));
+    initmaster(f);
+    *ttyn = TtyName;
+    return f;
+}
+#endif
+
+#if defined(__sgi) && !defined(PTY_DONE)
+#define PTY_DONE
+    int
+OpenPTY(ttyn)
+    char **ttyn;
+{
+    int f;
+    char *name;
+    RETSIGTYPE (*sigcld)__ARGS(SIGPROTOARG);
+
+    /*
+     * SIGCHLD set to SIG_DFL for _getpty() because it may fork() and
+     * exec() /usr/adm/mkpts
+     */
+    sigcld = signal(SIGCHLD, SIG_DFL);
+    name = _getpty(&f, O_RDWR | O_NONBLOCK | O_EXTRA, 0600, 0);
+    signal(SIGCHLD, sigcld);
+
+    if (name == 0)
+	return -1;
+    initmaster(f);
+    *ttyn = name;
+    return f;
+}
+#endif
+
+#if defined(MIPS) && defined(HAVE_DEV_PTC) && !defined(PTY_DONE)
+#define PTY_DONE
+    int
+OpenPTY(ttyn)
+    char **ttyn;
+{
+    int		f;
+    struct stat buf;
+    /* used for opening a new pty-pair: */
+    static char TtyName[32];
+
+    if ((f = open("/dev/ptc", O_RDWR | O_NOCTTY | O_NONBLOCK | O_EXTRA, 0)) < 0)
+	return -1;
+    if (mch_fstat(f, &buf) < 0)
+    {
+	close(f);
+	return -1;
+    }
+    sprintf(TtyName, "/dev/ttyq%d", minor(buf.st_rdev));
+    initmaster(f);
+    *ttyn = TtyName;
+    return f;
+}
+#endif
+
+#if defined(HAVE_SVR4_PTYS) && !defined(PTY_DONE) && !defined(hpux)
+
+/* NOTE: Even though HPUX can have /dev/ptmx, the code below doesn't work! */
+#define PTY_DONE
+    int
+OpenPTY(ttyn)
+    char **ttyn;
+{
+    int		f;
+    char	*m, *ptsname();
+    int unlockpt __ARGS((int)), grantpt __ARGS((int));
+    RETSIGTYPE (*sigcld)__ARGS(SIGPROTOARG);
+    /* used for opening a new pty-pair: */
+    static char TtyName[32];
+
+    if ((f = open("/dev/ptmx", O_RDWR | O_NOCTTY | O_EXTRA, 0)) == -1)
+	return -1;
+
+    /*
+     * SIGCHLD set to SIG_DFL for grantpt() because it fork()s and
+     * exec()s pt_chmod
+     */
+    sigcld = signal(SIGCHLD, SIG_DFL);
+    if ((m = ptsname(f)) == NULL || grantpt(f) || unlockpt(f))
+    {
+	signal(SIGCHLD, sigcld);
+	close(f);
+	return -1;
+    }
+    signal(SIGCHLD, sigcld);
+    strncpy(TtyName, m, sizeof(TtyName));
+    initmaster(f);
+    *ttyn = TtyName;
+    return f;
+}
+#endif
+
+#if defined(_AIX) && defined(HAVE_DEV_PTC) && !defined(PTY_DONE)
+#define PTY_DONE
+
+#ifdef _IBMR2
+int aixhack = -1;
+#endif
+
+    int
+OpenPTY(ttyn)
+    char **ttyn;
+{
+    int		f;
+    /* used for opening a new pty-pair: */
+    static char TtyName[32];
+
+    /* a dumb looking loop replaced by mycrofts code: */
+    if ((f = open("/dev/ptc", O_RDWR | O_NOCTTY | O_EXTRA)) < 0)
+	return -1;
+    strncpy(TtyName, ttyname(f), sizeof(TtyName));
+    if (geteuid() && mch_access(TtyName, R_OK | W_OK))
+    {
+	close(f);
+	return -1;
+    }
+    initmaster(f);
+# ifdef _IBMR2
+    if (aixhack >= 0)
+	close(aixhack);
+    if ((aixhack = open(TtyName, O_RDWR | O_NOCTTY | O_EXTRA, 0)) < 0)
+    {
+	close(f);
+	return -1;
+    }
+# endif
+    *ttyn = TtyName;
+    return f;
+}
+#endif
+
+#ifndef PTY_DONE
+
+# ifdef hpux
+static char PtyProto[] = "/dev/ptym/ptyXY";
+static char TtyProto[] = "/dev/pty/ttyXY";
+# else
+#  ifdef __BEOS__
+static char PtyProto[] = "/dev/pt/XY";
+static char TtyProto[] = "/dev/tt/XY";
+#  else
+static char PtyProto[] = "/dev/ptyXY";
+static char TtyProto[] = "/dev/ttyXY";
+#  endif
+# endif
+
+    int
+OpenPTY(ttyn)
+    char **ttyn;
+{
+    char	*p, *q, *l, *d;
+    int		f;
+    /* used for opening a new pty-pair: */
+    static char PtyName[32];
+    static char TtyName[32];
+
+    strcpy(PtyName, PtyProto);
+    strcpy(TtyName, TtyProto);
+    for (p = PtyName; *p != 'X'; p++)
+	;
+    for (q = TtyName; *q != 'X'; q++)
+	;
+    for (l = PTYRANGE0; (*p = *l) != '\0'; l++)
+    {
+	for (d = PTYRANGE1; (p[1] = *d) != '\0'; d++)
+	{
+#if !defined(MACOS) || defined(USE_CARBONIZED)
+	    if ((f = open(PtyName, O_RDWR | O_NOCTTY | O_EXTRA, 0)) == -1)
+#else
+	    if ((f = open(PtyName, O_RDWR | O_NOCTTY | O_EXTRA)) == -1)
+#endif
+		continue;
+	    q[0] = *l;
+	    q[1] = *d;
+#ifndef MACOS
+	    if (geteuid() && mch_access(TtyName, R_OK | W_OK))
+	    {
+		close(f);
+		continue;
+	    }
+#endif
+#if defined(sun) && defined(TIOCGPGRP) && !defined(SUNOS3)
+	    /* Hack to ensure that the slave side of the pty is
+	     * unused. May not work in anything other than SunOS4.1
+	     */
+	    {
+		int pgrp;
+
+		/* tcgetpgrp does not work (uses TIOCGETPGRP)! */
+		if (ioctl(f, TIOCGPGRP, (char *)&pgrp) != -1 || errno != EIO)
+		{
+		    close(f);
+		    continue;
+		}
+	    }
+#endif
+	    initmaster(f);
+	    *ttyn = TtyName;
+	    return f;
+	}
+    }
+    return -1;
+}
+#endif