From b908e772efd26043e25f2b0a9d972a126d4be11d Mon Sep 17 00:00:00 2001
From: Brad Grantham <grantham@plunk.org>
Date: Sat, 2 Jan 2021 07:53:46 -0800
Subject: [PATCH] only invalidate track if drive wasn't selected before

---
 apple2e.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/apple2e.cpp b/apple2e.cpp
index 9618020..86209ac 100644
--- a/apple2e.cpp
+++ b/apple2e.cpp
@@ -1020,14 +1020,18 @@ struct DISKIIboard : board_base
             return true;
         } else if(addr == SELECT) {
             if(debug & DEBUG_FLOPPY) printf("floppy select first drive\n");
-            driveSelected = 0;
-            trackBytesOutOfDate = true;
+            if(driveSelected != 0) {
+                driveSelected = 0;
+                trackBytesOutOfDate = true;
+            }
             data = 0;
             return true;
         } else if(addr == SELECT + 1) {
             if(debug & DEBUG_FLOPPY) printf("floppy select second drive\n");
-            driveSelected = 1;
-            trackBytesOutOfDate = true;
+            if(driveSelected != 1) {
+                driveSelected = 1;
+                trackBytesOutOfDate = true;
+            }
             data = 0;
             return true;
         } else if(addr == ENABLE) {