From 1db917434aa9c080443703f5131ff77ccb6d2ff7 Mon Sep 17 00:00:00 2001
From: Paul Gardner-Stephen <paul@servalproject.org>
Date: Sun, 19 Nov 2017 07:30:41 +1100
Subject: [PATCH] write to chipram and shadow ram when writing to colour RAM
 via $1F800-$1FFFF

---
 src/vhdl/gs4510.vhdl | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/vhdl/gs4510.vhdl b/src/vhdl/gs4510.vhdl
index 976a571e7..35c910a99 100644
--- a/src/vhdl/gs4510.vhdl
+++ b/src/vhdl/gs4510.vhdl
@@ -2107,9 +2107,23 @@ begin
 
       
       if real_long_address(27 downto 12) = x"001F" and real_long_address(11)='1' then
-        -- colour ram access: remap to $FF80000 - $FF807FF
+	-- Colour RAM writing is complex! we have to write also to chip and
+        -- shadow RAM.
+
+	-- Write to shadow RAM
+        shadow_write <= '1';
+        rom_write <= '0';
+        shadow_write_flags(3) <= '1';
+
+        -- Write to CHIP RAM
+        chipram_address <= long_address(16 downto 0);
+        chipram_we <= '1';
+        chipram_datain <= value;
+        report "writing to chipram..." severity note;
+        
+        -- Then remap to colour ram access: remap to $FF80000 - $FF807FF
         long_address := x"FF80"&'0'&real_long_address(10 downto 0);
-		  
+
       elsif real_long_address(27 downto 16) = x"7F4" then
 		  long_address := x"FF80"&'0'&real_long_address(10 downto 0);
       else