diff --git a/libsrc/c128/c128.inc b/libsrc/c128/c128.inc
index e22c29fcf..c8e65bc31 100644
--- a/libsrc/c128/c128.inc
+++ b/libsrc/c128/c128.inc
@@ -176,7 +176,9 @@ CIA2_CRB	= $DD0F
 ; I/O: MMU
 
 MMU_CR		= $FF00
-CC65_MMU_CFG	= $0E	; Bank 0 with kernal ROM
+MMU_CFG_CC65    = %00001110	; Bank 0 with kernal ROM
+MMU_CFG_RAM0	= %00111111	; Bank 0 full RAM
+
 
 ; ---------------------------------------------------------------------------
 ; Super CPU
diff --git a/libsrc/c128/crt0.s b/libsrc/c128/crt0.s
index 3a2b888e6..62501722a 100644
--- a/libsrc/c128/crt0.s
+++ b/libsrc/c128/crt0.s
@@ -61,7 +61,7 @@ Head:   .word   @Next
 
 	lda	MMU_CR	 	; Get current memory configuration...
        	pha		 	; ...and save it for later
-       	lda    	#CC65_MMU_CFG	; Bank0 with kernal ROM
+       	lda    	#MMU_CFG_CC65	; Bank0 with kernal ROM
     	sta	MMU_CR
 
 ; Save the zero page locations we need
@@ -178,7 +178,7 @@ IRQStub:
 	cld    	       		   	; Just to be sure
 	lda     MMU_CR 		   	; Get old register value
 	pha    	       		   	; And save on stack
-	lda     #CC65_MMU_CFG	   	; Bank 0 with kernal ROM
+	lda     #MMU_CFG_CC65		; Bank 0 with kernal ROM
 	sta    	MMU_CR
 	ldy 	#<(__IRQFUNC_COUNT__*2)
        	lda    	#<__IRQFUNC_TABLE__
diff --git a/libsrc/c128/rs232.s b/libsrc/c128/rs232.s
index 821890224..a1f3f6a3f 100644
--- a/libsrc/c128/rs232.s
+++ b/libsrc/c128/rs232.s
@@ -541,7 +541,7 @@ _rs232_status:
 .segment       	"LOWCODE"
 
 NmiHandler:
-	lda	#CC65_MMU_CFG		;(2)
+	lda	#MMU_CFG_CC65		;(2)
      	sta	MMU_CR 			;(4)
        	lda    	ACIA+RegStatus       	;(4) ;status ;check for byte received
      	and 	#$08           		;(2)