Changeset 597 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Initialization/DetectDrives.asm

Timestamp:

Jul 11, 2018, 9:44:43 AM (6 years ago)

Author:

aitotat

Message:

Windows 95 CMOS hack now works with Award BIOSes.
Some small optimizations to INT 19h and INT 19h reset handlers.
Added menuitem to configurator for clearing BDA drive count.

File:

• trunk/XTIDE_Universal_BIOS/Src/Initialization/DetectDrives.asm (modified) (1 diff)

trunk/XTIDE_Universal_BIOS/Src/Initialization/DetectDrives.asm

@@ -118 +118 @@
         jnz     SHORT .ClearBdaDriveCount       ; Unsupported BIOS, use plan B
 
-        ; Now we can alter CMOS location 12h
+        ; Now we can alter CMOS location 12h. Important! We set type for drive 1
+        ; (primary slave) and not for drive 0! Award BIOS locks if we set drive 0 type to Fh.
+        ; We cannot set it to less either since that will fully set predefined hard drive type to the BIOS.
+        ; Windows 95 only cares that the CMOS location 12h is non-zero.
         mov     dl, HARD_DISK_TYPES
-        mov     al, 0F0h    ; Drive 0 type 16...47 but Windows doesn't care as long as this is not zero
+        mov     al, 0Fh ; Drive 1 type 16...47 (defined elsewhere in the CMOS)
         call    CMOS_WriteALtoIndexInDL
         call    CMOS_StoreNewChecksumFor10hto2Dh