fix typos

sys/msdos/Install.dos

@@ -66,7 +66,7 @@ II. There once was a time when people built NetHack right on their DOS machine.
         CROSS_TO_MSDOS=1
     on your make command line.
 
-    Note: Both the fetch-cross-compiler.sh script and and the msdos
+    Note: Both the fetch-cross-compiler.sh script and the msdos
     cross-compile and package procedures require unzip and zip to be available
     on your host build system.
 

sys/msdos/video.c

@@ -111,7 +111,7 @@ typedef long clock_t;
 #include <dos.h> /* needed for delay() */
 #endif
 
-#ifdef SCREEN_DJGPPFAST /* parts of this block may be unecessary now */
+#ifdef SCREEN_DJGPPFAST /* parts of this block may be unnecessary now */
 #define get_cursor(x, y) ScreenGetCursor(y, x)
 #endif
 
@@ -134,7 +134,7 @@ int attrib_gr_normal;        /* graphics mode normal attribute */
 int attrib_text_intense;     /* text mode intense attribute */
 int attrib_gr_intense;       /* graphics mode intense attribute */
 uint32 curframecolor = NO_COLOR;   /* current background text color */
-boolean traditional = FALSE; /* traditonal TTY character mode */
+boolean traditional = FALSE; /* traditional TTY character mode */
 boolean inmap = FALSE;       /* in the map window */
 char ttycolors[CLR_MAX]; /* also used/set in options.c */
 

sys/msdos/vidvesa.c

@@ -1340,7 +1340,7 @@ vesa_FontPtrs(void)
 }
 
 /*
- * This will verify the existance of a VGA adapter on the machine.
+ * This will verify the existence of a VGA adapter on the machine.
  * Video function call 0x4F00 returns 0x004F in AX if successful, and
  * returns a VbeInfoBlock describing the features of the VESA BIOS.
  */
@@ -1628,7 +1628,7 @@ vesa_WriteCharXY(uint32 chr, int pixx, int pixy, uint32 colour)
 
 /*
  * Draw a character with a transparent background
- * Don't bother cacheing; only the position bar and the cursor use this
+ * Don't bother caching; only the position bar and the cursor use this
  */
 static void
 vesa_WriteCharTransparent(int chr, int pixx, int pixy, int colour)

sys/msdos/vidvga.c

@@ -917,7 +917,7 @@ vga_FontPtrs(void)
 }
 
 /*
- * This will verify the existance of a VGA adapter on the machine.
+ * This will verify the existence of a VGA adapter on the machine.
  * Video function call 0x1a returns 0x1a in AL if successful, and
  * returns the following values in BL for the active display:
  *