From 9c6a93029e0c77479807846962dc680f0b70dc38 Mon Sep 17 00:00:00 2001
From: Peter Ferrie <peter.ferrie@gmail.com>
Date: Thu, 30 Jul 2020 10:21:42 -0700
Subject: [PATCH] stable exit to GS/OS

---
 src/4cade.a           | 5 +++++
 src/4cade.init.a      | 8 +++++++-
 src/constants.a       | 3 +--
 src/glue.launch.lc2.a | 5 -----
 4 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/4cade.a b/src/4cade.a
index db0c9a5d7..04963b957 100644
--- a/src/4cade.a
+++ b/src/4cade.a
@@ -46,6 +46,11 @@ Reenter
          jsr   DisableAccelerator    ; back to 1 MHz (especially important on IIgs
                                      ; which restores default speed on Ctrl-Reset)
          jsr   CloseHandles          ; close any open handles to restore ProRWTS
+         ldx   #(end_promote-promote-1)
+-        lda   promote,x             ; copy ProDOS shim to main memory for GS/OS exit
+         sta   $bf00,x
+         dex
+         bpl   -
          ldx   #5
 -        lda   ResetVector,x         ; copy reentry wrapper to bottom of stack
          sta   $100,x                ; (used as reset vector because //e always
diff --git a/src/4cade.init.a b/src/4cade.init.a
index b66669aa0..f729a2ef5 100644
--- a/src/4cade.init.a
+++ b/src/4cade.init.a
@@ -336,7 +336,7 @@ OneTimeSetup
          lda   $E100BD               ; Make sure GS/OS was the boot OS
 !cpu 6502
          beq   @NotGSOS
-         ldx   #5
+         ldx   #(QuitToGSOS_e-QuitToGSOS)-1
 -        lda   QuitToGSOS,x
          sta   PatchQuit,x
          dex
@@ -454,8 +454,14 @@ CopyDevs
          !byte 1
 
 QuitToGSOS
+         lda   #$8B
+         sta   ProDOS_exit+1         ; restore bank 1
+         lda   #$FF                  ; no prefix
+         sta   ProDOS_prefix
+
 !cpu 65816
          clc
          xce
          jmp   $E0D000
 !cpu 6502
+QuitToGSOS_e
diff --git a/src/constants.a b/src/constants.a
index 3d1c50993..67674fc23 100644
--- a/src/constants.a
+++ b/src/constants.a
@@ -7,8 +7,7 @@
 ;
 ; LC RAM BANK 1
 ; D000..E908 - persistent data structures (gGlobalPrefsStore, gGamesListStore)
-; ...unused...
-; E914..FFF1 - main program code
+; E909..FFF1 - main program code
 ; FFF2..FFF9 - API functions and global constants available for main program
 ;              code, prelaunchers, transition effects, &c.
 ;              (Wait/UnwaitForVBL, MockingboardStuff, MachineStatus)
diff --git a/src/glue.launch.lc2.a b/src/glue.launch.lc2.a
index c439a020f..f62863b5c 100644
--- a/src/glue.launch.lc2.a
+++ b/src/glue.launch.lc2.a
@@ -18,11 +18,6 @@ LaunchInternal
          sty   RestoreStackNextTime + 1
                                      ; tell |Reenter| to restore the stack and stack pointer
 
-         ldx   #(end_promote-promote-1)
--        lda   promote,x             ; copy ProDOS shim to main memory
-         sta   $bf00,x
-         dex
-         bpl   -
          tya
          ldy   #$18
 -        sta   $bf57,y