diff -ru grub-0.97_orig/stage1/stage1.S grub-0.97/stage1/stage1.S
--- grub-0.97_orig/stage1/stage1.S	2005-02-15 22:54:31.000000000 +0100
+++ grub-0.97/stage1/stage1.S	2009-03-24 21:12:57.000000000 +0100
@@ -162,24 +162,37 @@
 	movw	$0x55aa, %bx
 	int	$0x13
 
+  /* mac pro hack */
+  /* cannot disturb %bx or carry flag until `sbbw' below */
+  mov    $0x8000fa90, %eax
+  mov    $0xcf8, %dx
+  out    %eax, (%dx)
+  mov    $0x40, %al
+  mov    $0xfc, %dl	/* %edx = 0xcfc */
+  out    %al, (%dx)
+
 	/* 
 	 *  %dl may have been clobbered by INT 13, AH=41H.
 	 *  This happens, for example, with AST BIOS 1.04.
+	 *  Plus it's definitely clobbered by mac pro hack.
 	 */
 	popw	%dx
 	pushw	%dx
 
 	/* use CHS if fails */
-	jc	chs_mode
-	cmpw	$0xaa55, %bx
+#	jc	chs_mode	/* `sbbw' and a single jump saves two bytes. */
+#	cmpw	$0xaa55, %bx	/* It's wrong if int 13(ah=41) returns carry */
+	sbbw	$0xaa55, %bx	/* && bx == 0xaa54... but that won't happen. */
 	jne	chs_mode
 
 	/* check if AH=0x42 is supported if FORCE_LBA is zero */
 	MOV_MEM_TO_AL(ABS(force_lba))	/* movb	ABS(force_lba), %al */
 	testb	%al, %al
 	jnz	lba_mode
-	andw	$1, %cx
-	jz	chs_mode
+#	andw    $1, %cx
+#	jz      chs_mode
+	rorb	$1, %cl		/* int 13(ah=41): extended disk access fns supported? */
+	jnc	chs_mode	/* rorb saves 1 byte, needs different condition code. */
 	
 lba_mode:
 	/* save the total number of sectors */
@@ -194,10 +207,12 @@
 	movl	ABS(stage2_sector), %ebx
 
 	/* the size and the reserved byte */
-	movw	$0x0010, (%si)
+#	movw	$0x0010, (%si)		/* see below... */
 
 	/* the blocks */
-	movw	$1, 2(%si)
+#	movw	$1, 2(%si)		/* see below... */
+
+	movl	$0x00010010,(%si)	/* ... combining these saves 2 code bytes */
 	
 	/* the absolute address (low 32 bits) */
 	movl	%ebx, 8(%si)
@@ -250,10 +265,11 @@
 	movw	$ABS(sectors), %si
 
 	/* set the mode to zero */
-	movb	$0, -1(%si)
+#	movb	$0, -1(%si)		/* see below... */
 	
 	/* save number of heads */
 	xorl	%eax, %eax
+	movb	%al, -1(%si)		/* ... mode = 0, saving 1 byte */
 	movb	%dh, %al
 	incw	%ax
 	movl	%eax, 4(%si)