Changeset 606 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs

Timestamp:

May 15, 2021, 8:27:11 PM (4 years ago)

Author:

Krister Nordvall

Message:

Changes:

• RESERVE_DIAGNOSTIC_CYLINDER has been completely removed as it wasted hard drive space, caused a compatibility problem with 32-bit disk access drivers under Windows 3.x and most importantly, it was in fact not needed since the same thing can be accomplished using the "User specified CHS" feature in XTIDECFG which is better because that applies only to that specific drive instead of all drives under XUB control.
• In BIOS builds containing MODULE_EBIOS (i.e. all official builds except the Tiny build), drives with a cylinder count less than or equal to 1024 had CHS translation applied to them unnecessarily if CHS translation method was set to Auto (which is the default). This bug has been present for a long time and, as a side effect, made RESERVE_DIAGNOSTIC_CYLINDER useless since the idea behind that was to provide compatibility with other old BIOSes using NORMAL addressing mode. WARNING! With this bug now being fixed, upgrading to this revision of the BIOS will require repartitioning and reformatting any drives affected by this (BIOSDRVS.COM can be helpful in determining which drives are affected).

Location:

trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs

Files:

• AtaGeometry.asm (modified) (4 diffs)
• CreateDPT.asm (modified) (1 diff)

trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/AtaGeometry.asm

@@ -74 +74 @@
 ;       BH:     Number of L-CHS sectors per track (1...63)
 ;       CX:     Number of bits shifted (0...3)
-;       DL:     CHS Translate Mode
-;   Corrupts registers:
-;       DH
+;       DX:     CHS Translate Mode
+;   Corrupts registers:
+;       Nothing
 ;--------------------------------------------------------------------
 AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIwithTranslateModeInDX:
@@ -100 +100 @@
     cmp     ax, 8192
     jbe     SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
+%else
+    ; Check if the drive is within the limits of NORMAL addressing.
+    ; If it is, then no CHS translation is necessary.
+    cmp     ax, MAX_LCHS_CYLINDERS
+    jbe     SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
 %endif
 
@@ -161 +166 @@
 ;       BH:     Number of sectors per track (always 63)
 ;       CX:     Number of bits shifted (0)
-;       DL:     TRANSLATEMODE_ASSISTED_LBA
-;   Corrupts registers:
-;       DH
+;       DX:     TRANSLATEMODE_ASSISTED_LBA
+;   Corrupts registers:
+;       Nothing
 ;--------------------------------------------------------------------
 ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH:
@@ -213 +218 @@
     xchg    bh, cl                      ; Sectors per Track to BH, zero to CL (CX)
     mov     dl, TRANSLATEMODE_ASSISTED_LBA
+    ; All combinations of value CH from 1 to 262128 divided by number of heads
+    ; (16/32/64/128/255) has been verified to return with DH cleared.
 ReturnLCHSinAXBLBH:
     ret

trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm

@@ -108 +108 @@
     ; Store P-CHS and flags
     call    AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI
-    dec     dl                      ; Set ZF if TRANSLATEMODE_LARGE, SF if TRANSLATEMODE_NORMAL
+    dec     dx                      ; Set ZF if TRANSLATEMODE_LARGE, SF if TRANSLATEMODE_NORMAL
     jle     SHORT .JumpOverSetBitForAssistedLBA