use __RESERVED_MEMORY__ to reserve memory for the default 20x24 text screen

diff --git a/cfg/atari5200.cfg b/cfg/atari5200.cfg
index ff74f2b7cb9b86aa12bd8f971e93ab5214a01a6c..294cad26ea01ca2dea4fbb7c4e5fdd66732bb6d2 100644 (file)
--- a/cfg/atari5200.cfg
+++ b/cfg/atari5200.cfg
@@ -1,14 +1,15 @@
 SYMBOLS {
-    __CARTSIZE__:   type = weak, value = $4000; # possible values: $4000 and $8000
-    __CART_ENTRY__: type = import;
-    __STACKSIZE__:  type = weak, value = $0300; # 3 pages stack
+    __CARTSIZE__:        type = weak,   value = $4000;   # possible values: $4000 and $8000
+    __CART_ENTRY__:      type = import;
+    __STACKSIZE__:       type = weak,   value = $0400;   # 4 pages stack
+    __RESERVED_MEMORY__: type = export, value = $0200;   # space for display list and 20x24 screen buffer
 }
 MEMORY {
-    ZP:        file = "", start = $0019,                size = $00E7,                         define = yes;
-    RAM:       file = "", start = $021C,                size = $4000 - __STACKSIZE__ - $021C, define = yes;
-    ROM:       file = %O, start = $C000 - __CARTSIZE__, size = __CARTSIZE__ - $18,            define = yes, fill = yes, fillval = $FF;
-    CARTNAME:  file = %O, start = $BFE8,                size = $0014                                        fill = yes, fillval = $40;
-    CARTYEAR:  file = %O, start = $BFFC,                size = $0002                                        fill = yes, fillval = $59;
+    ZP:        file = "", start = $0019,                size = $00E7,                                               define = yes;
+    RAM:       file = "", start = $021C,                size = $4000 - __STACKSIZE__ - __RESERVED_MEMORY__ - $021C, define = yes;
+    ROM:       file = %O, start = $C000 - __CARTSIZE__, size = __CARTSIZE__ - $18,                                  define = yes, fill = yes, fillval = $FF;
+    CARTNAME:  file = %O, start = $BFE8,                size = $0014                                                              fill = yes, fillval = $40;
+    CARTYEAR:  file = %O, start = $BFFC,                size = $0002                                                              fill = yes, fillval = $59;
     CARTENTRY: file = %O, start = $BFFE,                size = $0002;
 }
 SEGMENTS {

diff --git a/libsrc/atari5200/crt0.s b/libsrc/atari5200/crt0.s
index 3944cd2bf7f62771617298e3e8b44a114336cfb7..56b58a541928f10fdb99871c60fd499cc7201723 100644 (file)
--- a/libsrc/atari5200/crt0.s
+++ b/libsrc/atari5200/crt0.s
@@ -6,8 +6,8 @@
 
         .export         _exit, start
         .export         __STARTUP__ : absolute = 1      ; Mark as startup
-       .import         __RAM_START__, __RAM_SIZE__
-       .import         __RESERVED_MEMORY__
+        .import         __RAM_START__, __RAM_SIZE__
+        .import         __RESERVED_MEMORY__
 
         .import         initlib, donelib, callmain
         .import         zerobss, copydata
@@ -32,9 +32,9 @@ start:
 
 ; setup the stack
 
-        lda     #<(__RAM_START__ + __RAM_SIZE__)
+        lda     #<(__RAM_START__ + __RAM_SIZE__ - __RESERVED_MEMORY__)
         sta     sp
-        lda     #>(__RAM_START__ + __RAM_SIZE__)
+        lda     #>(__RAM_START__ + __RAM_SIZE__ - __RESERVED_MEMORY__)
         sta     sp+1            ; Set argument stack ptr
 
 ; Call module constructors