Changeset 593 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Initialization/DetectDrives.asm

Timestamp:

Jun 30, 2018, 8:27:04 AM (7 years ago)

Author:

Tomi Tilli

Message:

Flashing now works again.
Hack to get Windows 95 to work properly (MODULE_WIN95_CMOS_HACK included for 386 builds by default).
Edited makefile to produce large 386 build.
Fixed recovery time for QDI Vision VLB-IDE controllers.
No more warnings with Nasm 2.13.xx and later.
File dialog now properly restores default drive when file selection is cancelled.

File:

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

trunk/XTIDE_Universal_BIOS/Src/Initialization/DetectDrives.asm

@@ -95 +95 @@
 ; FindDPT_ForDriveNumber will not find any drives that are ours.
 ;
+
+; Here we might want to replace BIOS configured drives with the ones we detected.
+; Primary reason is to support dynamic overlay feature in the future. Second reason
+; is a hack to get Windows 95 load proper IDE drivers.
+; 
+; The Windows hack has two parts. First part is to try to alter CMOS address 12h as that
+; is what Windows 95 driver reads to detect IDE drives. Altering is not possible on all
+; systems since CMOS has a checksum but it's location is not standardized. We will first
+; try to detect valid checksum. If it succeeds, then it is safe to assume this system
+; has compatible CMOS and we can alter it.
+; If verify fails, we do the more dirty hack to zero BDA drive count. Then Windows 95 works
+; as long as user has configured at least one drive in the BIOS setup.
+
+%ifdef USE_AT   ; FLG_ROMVARS_IGNORE_MOTHERBOARD_DRIVES is for AT builds only
+
+    %ifdef MODULE_WIN95_CMOS_HACK
+        mov     dl, HARD_DISK_TYPES
+        call    CMOS_ReadFromIndexInDLtoAL
+        test    al, al
+        jnz     SHORT .ContinueInitialization   ; CMOS byte 12h is ready for Windows 95
+        call    CMOS_Verify10hTo2Dh
+        jnz     SHORT .ClearBdaDriveCount       ; Unsupported BIOS, use plan B
+    
+        ; Now we can alter CMOS location 12h
+        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
+        call    CMOS_WriteALtoIndexInDL
+        call    CMOS_StoreNewChecksumFor10hto2Dh
+    %endif
+
+    test    BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_IGNORE_MOTHERBOARD_DRIVES
+    jz      SHORT .ContinueInitialization
+.ClearBdaDriveCount:
+    mov     BYTE [es:BDA.bHDCount], 0   ; Set hard disk count to zero
+.ContinueInitialization:
+%endif
+
     mov     cx, [RAMVARS.wDrvCntAndFlopCnt]     ; Our count of hard disks
     mov     al, [es:BDA.bHDCount]