diff --git a/source/Interrupt List/INT 21 DOS Function Calls/INT 2130 DOS 2 GET DOS VERSION.txt b/source/Interrupt List/INT 21 DOS Function Calls/INT 2130 DOS 2 GET DOS VERSION.txt
index 102020c0..79d1ceaf 100644
--- a/source/Interrupt List/INT 21 DOS Function Calls/INT 2130 DOS 2 GET DOS VERSION.txt	
+++ b/source/Interrupt List/INT 21 DOS Function Calls/INT 2130 DOS 2 GET DOS VERSION.txt	
@@ -57,6 +57,8 @@ Notes:	the OS/2 v1.x Compatibility Box returns major version 0Ah (10)
 	  version y.
 	Enhanced DR-DOS as of v7.01.07 returns DR-DOS (OEM EEh) v6.00 here,
 	  but v7.01 on the MS-DOS v5+ function INT 21/AX=3306h"DOS".
+	DR DOS v9 (rev 648) returns DR-DOS (OEM EEh) v3.31 here and does not
+	  support the MS-DOS v5+ function INT 21/AX=3306h"DOS".
 	RxDOS v7.24 returns v7.24 on INT 21/AX=3306h"DOS" and either v7.10 (if
 	  FAT32 supported), v7.00 (if FAT32 not supported but LFN supported),
 	  or v6.22 (if both FAT32 and LFN not supported) on AH=30h.
@@ -166,7 +168,7 @@ Values for DOS OEM number:
  DCh -	Apparently used for DOS-C kernel (historically the base of the
 	 FreeDOS kernel) for some alternative builds.
  EDh -	reserved for future OpenDOS/DR-DOS based projects  http://www.drdos.org
- EEh	DR DOS (used for Enhanced DR-DOS since v7.01.07)
+ EEh	DR DOS (used for Enhanced DR-DOS since v7.01.07 and for DR DOS v9)
  EFh	Novell DOS
 	Note:	released versions of Novell DOS 7 use OEM ID 00h instead
  FDh	FreeDOS	 http://www.freedos.org/
diff --git a/source/Interrupt List/INT 21 DOS Function Calls/INT 214452 DR DOS 341 DETERMINE DOS TYPEGET DR DOS VERSION.txt b/source/Interrupt List/INT 21 DOS Function Calls/INT 214452 DR DOS 341 DETERMINE DOS TYPEGET DR DOS VERSION.txt
index 4e78da1e..d4010fd8 100644
--- a/source/Interrupt List/INT 21 DOS Function Calls/INT 214452 DR DOS 341 DETERMINE DOS TYPEGET DR DOS VERSION.txt	
+++ b/source/Interrupt List/INT 21 DOS Function Calls/INT 214452 DR DOS 341 DETERMINE DOS TYPEGET DR DOS VERSION.txt	
@@ -105,7 +105,7 @@ Values for Digital Research operating system version ID:
  63h	DR DOS 3.41
  64h	DR DOS 3.42
  65h	DR DOS 5.0
- 67h	DR DOS 6.0
+ 67h	DR DOS 6.0 (also used by DR DOS v9 rev 648)
  70h	PalmDOS
  71h	DR DOS 6.0 March 1993 "business update"
  72h	Novell DOS 7.0
@@ -224,6 +224,7 @@ Values for Digital Research operating system ID codes (full AX return value):
 	      The listed patches only address a single problem, while the
 	       listed updates are full rebuilds, also including all previous
 	       fixes.
+	- DR DOS v9 rev 648 as of 2026-05-12
  1070h	- multitasking "Vladivar" kernel architecture and introduction of
 	  DOS-like structures (1991-07-26, 08/1991)
 	- DR DOS ??? (1991-09-26)