new file mode 100644
--- /dev/null
+++ b/src/os_riscos.h
@@ -0,0 +1,169 @@
+/* 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.
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <termios.h>
+#include <stdlib.h>
+#include <unixlib/local.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#define CASE_INSENSITIVE_FILENAME
+#define FEAT_MODIFY_FNAME
+#define FEAT_OSFILETYPE
+#define DFLT_OFT	"Text"
+#define USE_TERM_CONSOLE
+#define HAVE_AVAIL_MEM
+
+/* Longer filenames now accessible to all */
+#ifndef BASENAMELEN
+# define BASENAMELEN 64 /* Same length as unzip */
+#endif
+
+#ifndef TEMNAME
+# define TEMPNAME	"<Wimp$ScrapDir>.v?XXXXXX"
+# define TEMPNAMELEN	25
+#endif
+
+#ifndef DFLT_HELPFILE
+# define DFLT_HELPFILE "Vim:doc.help"
+#endif
+
+#ifndef DFLT_BDIR
+# define DFLT_BDIR	".,<Wimp$ScrapDir>."	/* default for 'backupdir' */
+#endif
+
+/* Paths to try putting swap file in. */
+#ifndef DFLT_DIR
+# define DFLT_DIR	"<Wimp$ScrapDir>.,."	/* default for 'directory' */
+#endif
+
+#ifndef DFLT_VDIR
+# define DFLT_VDIR	"Choices:Vim.view"	/* default for 'viewdir' */
+#endif
+
+#ifndef TERMCAPFILE
+# define TERMCAPFILE	"Vim:TermCap"
+#endif
+#define HAVE_TGETENT
+
+#ifndef SYNTAX_FNAME
+# define SYNTAX_FNAME	"Vim:Syntax.%s"
+#endif
+
+#ifndef EVIM_FILE
+# define EVIM_FILE	"Vim:Evim"
+#endif
+
+#define FEAT_VIMINFO
+
+#ifndef VIMINFO_FILE
+# define VIMINFO_FILE	"<Choices$Write>.Vim.VimInfo"
+#endif
+#ifndef VIMINFO_FILE2
+# define VIMINFO_FILE2	"Choices:Vim.VimInfo"
+#endif
+
+#ifndef VIMRC_FILE
+# define VIMRC_FILE	"/vimrc"
+#endif
+#ifndef EXRC_FILE
+# define EXRC_FILE	"/exrc"
+#endif
+#ifndef GVIMRC_FILE
+# define GVIMRC_FILE	"/gvimrc"
+#endif
+#ifndef VIEW_FILE
+# define VIEW_FILE	"/View"
+#endif
+#ifndef USR_VIMRC_FILE
+# define USR_VIMRC_FILE	"Vim:Evim"
+#endif
+#ifndef SESSION_FILE
+# define SESSION_FILE	"/Session.vim"
+#endif
+#ifndef USR_VIMRC_FILE
+# define USR_VIMRC_FILE	"Choices:Vim.VimRC"
+#endif
+#ifndef USR_GVIMRC_FILE
+# define USR_GVIMRC_FILE    "Choices:Vim.GVimRC"
+#endif
+#ifndef USR_EXRC_FILE
+# define USR_EXRC_FILE    "Choices:Vim.ExRC"
+#endif
+#ifndef SYS_VIMRC_FILE
+# define SYS_VIMRC_FILE	    "Vim:VimRC"
+#endif
+#ifndef SYS_GVIMRC_FILE
+# define SYS_GVIMRC_FILE    "Vim:GVimRC"
+#endif
+#ifndef SYS_MENU_FILE
+# define SYS_MENU_FILE	    "Vim:Menu"
+#endif
+#ifndef SYS_OPTWIN_FILE
+# define SYS_OPTWIN_FILE    "Vim:Optwin"
+#endif
+#ifndef FILETYPE_FILE
+# define FILETYPE_FILE	    "Vim:Filetype"
+#endif
+#ifndef FTPLUGIN_FILE
+# define FTPLUGIN_FILE	    "Vim:Ftplugin/vim"
+#endif
+#ifndef INDENT_FILE
+# define INDENT_FILE	    "Vim:Indent/vim"
+#endif
+#ifndef FTOFF_FILE
+# define FTOFF_FILE	    "Vim:Ftoff"
+#endif
+#ifndef FTPLUGOF_FILE
+# define FTPLUGOF_FILE	    "Vim:Ftplugof"
+#endif
+#ifndef INDOFF_FILE
+# define INDOFF_FILE	    "Vim:Indoff"
+#endif
+
+#define DFLT_ERRORFILE		"errors/vim"
+#define DFLT_RUNTIMEPATH	"Choices:Vim,Vim:,Choices:Vim.after"
+
+/*
+ * RISC PCs have plenty of memory, use large buffers
+ */
+#define CMDBUFFSIZE 1024	/* size of the command processing buffer */
+#define MAXPATHL    256		/* paths are always quite short though */
+
+#ifndef DFLT_MAXMEM
+# define DFLT_MAXMEM	(5*1024)    /* use up to 5 Mbyte for a buffer */
+#endif
+
+#ifndef DFLT_MAXMEMTOT
+# define DFLT_MAXMEMTOT	(10*1024)    /* use up to 10 Mbyte for Vim */
+#endif
+
+#ifdef HAVE_SIGSET
+# define signal sigset
+#endif
+
+#define n_flag (1<<31)
+#define z_flag (1<<30)
+#define c_flag (1<<29)
+#define v_flag (1<<28)
+
+/* These take r0-r7 as inputs, returns r0-r7 in global variables. */
+void swi(int swinum, ...);      /* Handles errors itself */
+int xswi(int swinum, ...);      /* Returns errors using v flag */
+extern int r0, r1, r2, r3, r4, r5, r6, r7;  /* For return values */
+
+#include <kernel.h>
+#include <swis.h>
+
+#define mch_memmove(to, from, len) memmove((char *)(to), (char *)(from), len)
+#define mch_rename(src, dst) rename(src, dst)
+#define mch_getenv(x) (char_u *)getenv((char *)x)
+#define mch_setenv(name, val, x) setenv(name, val, x)