Fixed int25 & int26 error code.

msdos/int25.c

diff --git a/msdos/int25.c b/msdos/int25.c
index 19d4598..f7c806b 100644
--- a/msdos/int25.c
+++ b/msdos/int25.c
@@ -26,7 +26,7 @@
     if (!DRIVE_IsValid(AL_reg(context)))
     {
         SET_CFLAG(context);
-        AX_reg(context) = 0x0101;        /* unknown unit */
+        AX_reg(context) = 0x0201;        /* unknown unit */
         return;
     }
 

msdos/int26.c

diff --git a/msdos/int26.c b/msdos/int26.c
index 5ed4995..41a507d 100644
--- a/msdos/int26.c
+++ b/msdos/int26.c
@@ -24,7 +24,7 @@
     if (!DRIVE_IsValid(AL_reg(context)))
     {
         SET_CFLAG(context);
-        AX_reg(context) = 0x0101;        /* unknown unit */
+        AX_reg(context) = 0x0201;        /* unknown unit */
         return;
     }