Fix BPLCON4 update

diff --git a/drawing.cpp b/drawing.cpp
index 694f86f9544e523368696d2df62e1bc3d6e026c9..6c0fc6ce55a5e448790a196a5ce11e2f5ec8b378 100644 (file)
--- a/drawing.cpp
+++ b/drawing.cpp
@@ -2780,7 +2780,7 @@ static void expand_bplcon4_spr(uae_u16 v)
 static void expand_bplcon4_bm(uae_u16 v)
 {
        bplcon4_denise &= 0x00ff;
-       bplcon4_denise = v & 0xff00;
+       bplcon4_denise |= v & 0xff00;
        // Sprite bank change is 1 hires pixel faster than bitplane XOR change
        if (aga_mode && (bplcon4_denise >> 8) != bplcon4_denise_xor_val2) {
                bplcon4_denise_xor_val2 = bplcon4_denise >> 8;