Changeset 595 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Handlers/Int19h.asm

Timestamp:

Jul 7, 2018, 9:53:24 AM (7 years ago)

Author:

Tomi Tilli

Message:

• Int 19h reset handler now tries to boot from drive A before warm reset. This should help to get INT 10h hooked before launching booter games (meaning system reset without reseting interrupt vector table).
• Win 95 hack temporarily removed (module not included by default). Very limited testing shows that CMOS hack seems to work with AMI bios but locks on Award BIOS.

File:

• trunk/XTIDE_Universal_BIOS/Src/Handlers/Int19h.asm (modified) (3 diffs)

trunk/XTIDE_Universal_BIOS/Src/Handlers/Int19h.asm

@@ -200 +200 @@
 %endif
     clc
-    ;; fall through to Int19_JumpToBootSectorOrRomBoot
-
-;--------------------------------------------------------------------
-; Int19_JumpToBootSectorOrRomBoot
+    ;; fall through to Int19h_JumpToBootSectorOrRomBoot
+
+;--------------------------------------------------------------------
+; Int19h_JumpToBootSectorOrRomBoot
 ;
 ; Switches back to the POST stack, clears the DS and ES registers,
@@ -213 +213 @@
 ;       CF:     Set for Boot Sector Boot
 ;               Clear for ROM Boot
-;       ES:BX:  (if CF set) Ptr to boot sector
+;       ES:BX:  (if CF set) Ptr to boot sector (ES = zero)
 ;
 ;   Returns:
 ;       Never returns
 ;--------------------------------------------------------------------
-Int19_JumpToBootSectorOrRomBoot:
-    mov     cx, es      ; Preserve MBR segment (can't push because of stack change)
-    mov     ax, 0       ; NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF
+Int19h_JumpToBootSectorOrRomBoot:
+    mov     ax, es      ; Preserve MBR segment (can't push because of stack change)
+                        ; NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF
     SWITCH_BACK_TO_POST_STACK
 
 ; clear segment registers before boot sector or rom call
     mov     ds, ax
-    mov     es, ax
 %ifdef USE_386
     mov     fs, ax
@@ -233 +232 @@
 
 ; jump to boot sector
-    push    cx          ; sgment address for MBR
+    push    ax          ; sgment address for MBR
     push    bx          ; offset address for MBR
     retf                ; NOTE: DL is set to the drive number