diff --git a/frontend/a2sdl/main.go b/frontend/a2sdl/main.go
index c1e71cc..b49cfd8 100644
--- a/frontend/a2sdl/main.go
+++ b/frontend/a2sdl/main.go
@@ -151,25 +151,26 @@ func sdlRun(a *izapple2.Apple2) {
 
 var helpMessage = `
 
-        F1: Show/Hide help
-   Ctrl-F2: Reset
-        F4: Show/Hide CPU trace
-        F5: Fast/Normal speed
-   Ctrl-F5: Show speed
-        F6: Next screen mode
-        F7: Show/Hide pages
-       F10: Next character set
-  Ctrl-F10: Show/Hide character set
- Shift-F10: Show/Hide alternate text
-       F12: Save screen snapshot
-	 Pause: Pause the emulation
+          F1: Show/Hide help
+     Ctrl-F2: Reset
+          F4: Show/Hide CPU trace
+          F5: Fast/Normal speed
+     Ctrl-F5: Show speed
+          F6: Next screen mode
+          F7: Show/Hide pages
+         F10: Next character set
+    Ctrl-F10: Show/Hide character set
+   Shift-F10: Show/Hide alternate text
+         F12: Save screen snapshot
+       Pause: Pause the emulation
 
- Drop a file on the left or right
- side of the window to load a disk
+  Left alt or option key: Open-Apple
+ Right alt or option key: Closed-Apple
+
+Drop a file on the left or right
+side of the window to load a disk
 
  Run izapple2 -h for more options
-
- More info at
    https://github.com/ivanizag/izapple2
 `
 
diff --git a/keyboard.go b/keyboard.go
index 70447ab..261f60b 100644
--- a/keyboard.go
+++ b/keyboard.go
@@ -1,6 +1,9 @@
 package izapple2
 
-import "unicode"
+import (
+	"slices"
+	"unicode"
+)
 
 // KeyboardProvider provides a keyboard implementation
 type KeyboardProvider interface {
@@ -29,8 +32,19 @@ func (k *KeyboardChannel) PutText(text string) {
 	}
 }
 
+var macOptionChars = []rune("ı˝•£‰ ⁄‘’≈œæ€®†¥øπå∫∂ƒ™¶§∑©√ßµ„…≤≥çñŒÆ€‡∏fl¯ˇ˘‹›◊˙˚")
+var macOptionSubs = []rune("!\"·$%&/()=qwertyopasdfghjkxcvbm,.<>cnQWETPGJKLZXVNM")
+
 // PutRune sends a rune to the emulator if it is valid printable ASCII
 func (k *KeyboardChannel) PutRune(ch rune) {
+
+	// Some substitutions useful for Macs that transform chars with the option key
+	pos := slices.Index(macOptionChars, ch)
+	if pos >= 0 {
+		println("Mac option char: ", string(ch), " -> ", string(macOptionSubs[pos]))
+		ch = rune(macOptionSubs[pos])
+	}
+
 	// We will use computed text only for printable ASCII chars
 	if ch >= ' ' && ch <= '~' {
 		if k.a.IsForceCaps() && ch >= 'a' && ch <= 'z' {