# HG changeset patch
# User Laurens Holst <laurens@grauw.nl>
# Date 1644758020 -3600
#      Sun Feb 13 14:13:40 2022 +0100
# Node ID 32b0c4617f4ac033e265cc766be0e4260b2a24e8
# Parent  a352449043e77c81e5fc543d11709f7005ab57df
vdp_guide: Changing r#18 during VDP command also corrupts with sprites enabled.

Confirmed by Artrag and PingPong. See:
https://www.msx.org/forum/development/msx-development/screen-8-smooth-horizontal-scrolling?page=2#comment-62616
https://www.msx.org/forum/development/msx-development/screen-8-smooth-horizontal-scrolling?page=3#comment-423454

diff --git a/articles/vdp_guide.php b/articles/vdp_guide.php
--- a/articles/vdp_guide.php
+++ b/articles/vdp_guide.php
@@ -24,7 +24,11 @@
 
 <h2 id="r18cmd">Q: r#18 in combination with VDP commands corrupts VRAM?</h2>
 
-<p>A: Yes. This issue only occurs when you have the sprites (or screen) disabled. If you use the screen position adjust register while executing a copy command and with sprites disabled, it will corrupt the byte the VDP command is currently processing. So, if that is the case, you should wait with setting r#18 until the VDP’s CE bit indicates the current command is finished.</p>
+<p>A: Yes. If you use the screen position adjust register while executing a copy
+command, it will corrupt the byte the VDP command is currently processing. This
+occurs regardless of whether you have the sprites or screen enabled. So, if that
+is the case, you should wait with setting r#18 until the VDP’s CE bit indicates
+the current command is finished.</p>
 
 
 <h2 id="r18disp">Q: What about screensplits with the help of r#18?</h2>