diff --git a/src/video/vid_ps55da2.c b/src/video/vid_ps55da2.c
index 5098fa64d..c7c989c5e 100644
--- a/src/video/vid_ps55da2.c
+++ b/src/video/vid_ps55da2.c
@@ -1562,12 +1562,12 @@ The Font ROM can be accessed via 128 KB memory window located at A0000-BFFFFh.
  16000-17FFFh (B6000-B7FFFh) : Codepage 850 characters (13 x 30)
  18000-1A3FFh (B8000-BA3FFh) : CAD control icons and box drawing characters (32 x 32)
 
- Some models have the signature 80h, 01h placed at Bank 0:1AFFEh. (it disables hardware text drawing in OS/2 J1.3)
+ Some models have the signature 80h, 01h placed at Bank 0:1AFFEh. It disables Bitblt text drawing in OS/2 J1.3.
 
 [Font ROM Map (DA3, Traditional Chinese)]
  Bank 0 - 11 : Valid Font ROM data
- Bank 12 : Alias of bank 11 (At least, DOS T5.0 uses this on purpose.)
- Bank 13 : All addresses return 0xFF
+ Bank 12 : Alias of bank 11 (At least, DOS T5.0 uses this on purpose to obtain the SBCS font.)
+ Bank 13 : Filled by 0xFFh
 
 [Gaiji RAM Map (DA2)]
  Bank 0 00000-1FFFFh placed between A0000h-BFFFFh
diff --git a/src/video/vid_svga.c b/src/video/vid_svga.c
index 5d0db103b..db378b754 100644
--- a/src/video/vid_svga.c
+++ b/src/video/vid_svga.c
@@ -502,20 +502,19 @@ svga_in(uint16_t addr, void *priv)
             ret = svga->attrregs[svga->attraddr];
             break;
         case 0x3c2:
-            if (svga->cable_connected)
-            {
+            if (svga->cable_connected) {
                 if ((svga->vgapal[0].r + svga->vgapal[0].g + svga->vgapal[0].b) >= 0x4e)
                     ret = 0;
                 else
                     ret = 0x10;
-            }
-            else
-            {
+            /* Monitor is not connected to the planar VGA if the PS/55 Display Adapter is installed. */
+            } else {
                 /*
                    The IBM PS/55 Display Adapter has own Monitor Type Detection bit in the different I/O port (I/O 3E0h, 3E1h).
-                   When the monitor cable is connected to the Display Adapter, this port returns the value as 'no cable connection'.
+                   When the monitor cable is connected to the Display Adapter, the port 3C2h returns the value as 'no cable connection'.
                    The POST of PS/55 has an extra code that tries detecting the monitor on the planar VGA.
-                   If it fails, then the POST reads the NVRAM set by the reference diskette, and updates the BIOS Data Area (Mem 487h, 489h).
+                   If it fails, then the POST reads the NVRAM set by the reference diskette, and writes the BIOS Data Area (Mem 487h, 489h).
+                   MONCHK.EXE in the reference diskette uses both I/O ports to determine the monitor type, and writes the BDA.
                 */
                 if (svga->vgapal[0].r >= 10 || svga->vgapal[0].g >= 10 || svga->vgapal[0].b >= 10)
                     ret = 0;