From 69c213e18092ffbf5c0dcf1b6f697b52b7d5654f Mon Sep 17 00:00:00 2001
From: Angelo Salese <angelosa@users.noreply.github.com>
Date: Tue, 27 Dec 2011 15:28:28 +0000
Subject: [PATCH] MESS specific bug-fix, nw

---
 src/emu/video/pc_vga.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/src/emu/video/pc_vga.c b/src/emu/video/pc_vga.c
index 5dd875510fc..0e7322e2265 100644
--- a/src/emu/video/pc_vga.c
+++ b/src/emu/video/pc_vga.c
@@ -629,16 +629,14 @@ READ8_HANDLER( vga_port_03c0_r )
 
 	switch (offset)
 	{
+		case 0:
+			data = vga.attribute.index;
+			break;
 		case 1:
-			if (vga.attribute.state==0)
-			{
-				data = vga.attribute.index;
-			}
-			else
-			{
-				if ((vga.attribute.index&0x1f)<sizeof(vga.attribute.data))
-					data=vga.attribute.data[vga.attribute.index&0x1f];
-			}
+			if( vga.attribute.index & 0x20) // protection bit
+				data = 0xff; // TODO: actually undefined
+			else if ((vga.attribute.index&0x1f)<sizeof(vga.attribute.data))
+				data=vga.attribute.data[vga.attribute.index&0x1f];
 			break;
 
 		case 2:
@@ -766,8 +764,9 @@ WRITE8_HANDLER(vga_port_03c0_w)
 		}
 		else
 		{
-			if ((vga.attribute.index&0x1f)<sizeof(vga.attribute.data))
-				vga.attribute.data[vga.attribute.index&0x1f]=data;
+			if(!(vga.attribute.index & 0x20)) // protection bit
+				if ((vga.attribute.index&0x1f)<sizeof(vga.attribute.data))
+					vga.attribute.data[vga.attribute.index&0x1f]=data;
 		}
 		vga.attribute.state=!vga.attribute.state;
 		break;