small cleanup in BASIC, improved cartridge compatibility

Makefile

@@ -9,30 +9,31 @@ TESTTAPE = testsuite/testtape-c64-pal-turbo.tap
 SRCDIR_COMMON  = c64/aliases
 
 SRCDIR_BASIC   = $(SRCDIR_COMMON) \
-                c64/basic \
-                c64/basic/commands \
-                c64/basic/init \
-                c64/basic/rom_revision
+                 c64/basic \
+                 c64/basic/,stubs \
+                 c64/basic/commands \
+                 c64/basic/init \
+                 c64/basic/rom_revision
 
 SRCDIR_KERNAL  = $(SRCDIR_COMMON) \
-                c64/kernal \
-                c64/kernal/,stubs \
-                c64/kernal/assets \
-                c64/kernal/banking \
-                c64/kernal/iec \
-                c64/kernal/iec_fast \
-                c64/kernal/init \
-                c64/kernal/interrupts \
-                c64/kernal/iostack \
-                c64/kernal/jumptable \
-                c64/kernal/keyboard \
-                c64/kernal/memory \
-                c64/kernal/print \
-                c64/kernal/rom_revision \
-                c64/kernal/rs232 \
-                c64/kernal/screen \
-                c64/kernal/tape \
-                c64/kernal/time
+                 c64/kernal \
+                 c64/kernal/,stubs \
+                 c64/kernal/assets \
+                 c64/kernal/banking \
+                 c64/kernal/iec \
+                 c64/kernal/iec_fast \
+                 c64/kernal/init \
+                 c64/kernal/interrupts \
+                 c64/kernal/iostack \
+                 c64/kernal/jumptable \
+                 c64/kernal/keyboard \
+                 c64/kernal/memory \
+                 c64/kernal/print \
+                 c64/kernal/rom_revision \
+                 c64/kernal/rs232 \
+                 c64/kernal/screen \
+                 c64/kernal/tape \
+                 c64/kernal/time
 
 
 SRC_TOOLS  = $(wildcard src/tools/*.c,src/tools/*.cc)

c64/basic/init/basic_cold_start_internal.s

@@ -31,6 +31,11 @@ basic_cold_start_internal:
 	lda #>do_ILLEGAL_QUANTITY_error
 	sta USRADD+1
 
+	// Clear the BRK location address
+	lda #$00
+	sta CMP0+0
+	sta CMP0+1
+
 	// Print startup messages
 	jsr INITMSG
 

c64/basic/init/initmsg_real.s

@@ -5,6 +5,10 @@
 
 initmsg_real:
 
+	// Clear the screen first, some cartridges (like IEEE-488) leeave a mess on the screen
+	lda #147
+	jsr JCHROUT
+
 #if CONFIG_BANNER_SIMPLE
 
 	lda #<startup_banner