diff --git a/src/basic/engine_runtime/execute_line_statements.s b/src/basic/engine_runtime/execute_line_statements.s
index cd9dcfd3..1c500524 100644
--- a/src/basic/engine_runtime/execute_line_statements.s
+++ b/src/basic/engine_runtime/execute_line_statements.s
@@ -248,29 +248,33 @@ execute_line:
 	ldy #$02
 
 !ifdef CONFIG_MEMORY_MODEL_60K {
+	
 	ldx #<OLDTXT
 	jsr peek_under_roms
-} else ifdef CONFIG_MEMORY_MODEL_46K_OR_50K {
-	jsr peek_under_roms_via_OLDTXT ; XXX! speed-optimize - combine whole flow into one routine
-} else { ; CONFIG_MEMORY_MODEL_38K
-	lda (OLDTXT),y
-}
-
 	sta CURLIN+0
+
 	iny
-
-!ifdef CONFIG_MEMORY_MODEL_60K {
 	jsr peek_under_roms
-} else ifdef CONFIG_MEMORY_MODEL_46K_OR_50K {
-	jsr peek_under_roms_via_OLDTXT
-} else { ; CONFIG_MEMORY_MODEL_38K
-	lda (OLDTXT),y
-}
-
 	sta CURLIN+1
 
 	jmp execute_statements
 
+} else ifdef CONFIG_MEMORY_MODEL_46K_OR_50K {
+
+	jmp helper_execute_line_statements
+
+} else { ; CONFIG_MEMORY_MODEL_38K
+
+	lda (OLDTXT),y
+	sta CURLIN+0
+	
+	iny
+	lda (OLDTXT),y
+	sta CURLIN+1
+
+	jmp execute_statements
+}
+
 
 execute_statements_var_assign:
 
diff --git a/src/basic/engine_runtime/follow_link_to_next_line.s b/src/basic/engine_runtime/follow_link_to_next_line_38K_60K.s
similarity index 55%
rename from src/basic/engine_runtime/follow_link_to_next_line.s
rename to src/basic/engine_runtime/follow_link_to_next_line_38K_60K.s
index 42b697b4..c5e73711 100644
--- a/src/basic/engine_runtime/follow_link_to_next_line.s
+++ b/src/basic/engine_runtime/follow_link_to_next_line_38K_60K.s
@@ -2,29 +2,30 @@
 ;; #LAYOUT# *   BASIC_0 #TAKE
 ;; #LAYOUT# *   *       #IGNORE
 
+
+!ifndef CONFIG_MEMORY_MODEL_46K_OR_50K {
+
 follow_link_to_next_line:
 
 	ldy #0
-
-	; XXX! for models 46K/50K provide optimized version
 	
 !ifdef CONFIG_MEMORY_MODEL_60K {
+
 	ldx #<OLDTXT+0
 	jsr peek_under_roms
-} else ifdef CONFIG_MEMORY_MODEL_46K_OR_50K {
-	jsr peek_under_roms_via_OLDTXT
-} else { ; CONFIG_MEMORY_MODEL_38K
-	lda (OLDTXT),y
-}
 
 	pha
 	iny
 
-!ifdef CONFIG_MEMORY_MODEL_60K {
 	jsr peek_under_roms
-} else ifdef CONFIG_MEMORY_MODEL_46K_OR_50K {
-	jsr peek_under_roms_via_OLDTXT
+
 } else { ; CONFIG_MEMORY_MODEL_38K
+
+	lda (OLDTXT),y
+
+	pha
+	iny
+
 	lda (OLDTXT),y
 }
 
@@ -33,3 +34,4 @@ follow_link_to_next_line:
 	sta OLDTXT+0
 
 	rts
+}
diff --git a/src/basic/engine_runtime/follow_link_to_next_line_46K_50K.s b/src/basic/engine_runtime/follow_link_to_next_line_46K_50K.s
new file mode 100644
index 00000000..5891f52d
--- /dev/null
+++ b/src/basic/engine_runtime/follow_link_to_next_line_46K_50K.s
@@ -0,0 +1,31 @@
+;; #LAYOUT# STD *       #TAKE-HIGH
+;; #LAYOUT# *   BASIC_0 #TAKE-HIGH
+;; #LAYOUT# *   *       #IGNORE
+
+; This has to go $E000 or above - routine below banks out the main BASIC ROM!
+
+
+!ifdef CONFIG_MEMORY_MODEL_46K_OR_50K {
+
+follow_link_to_next_line:
+
+	; Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	ldy #0	
+	lda (OLDTXT), y
+	pha
+
+	iny
+	lda (OLDTXT), y
+
+	sta OLDTXT+1
+	pla
+	sta OLDTXT+0
+
+	// Restore default mapping and quit
+
+	jmp remap_BASIC
+}
diff --git a/src/basic/engine_runtime/helper_execute_line_statements_46K_50K.s b/src/basic/engine_runtime/helper_execute_line_statements_46K_50K.s
new file mode 100644
index 00000000..f03d430e
--- /dev/null
+++ b/src/basic/engine_runtime/helper_execute_line_statements_46K_50K.s
@@ -0,0 +1,32 @@
+;; #LAYOUT# STD *       #TAKE-HIGH
+;; #LAYOUT# *   BASIC_0 #TAKE-HIGH
+;; #LAYOUT# *   *       #IGNORE
+
+; This has to go $E000 or above - routine below banks out the main BASIC ROM!
+
+
+!ifdef CONFIG_MEMORY_MODEL_46K_OR_50K {
+
+helper_execute_line_statements:
+
+	; Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	; Update CURLIN
+
+	lda (OLDTXT), y
+	sta CURLIN+0
+	
+	iny
+	lda (OLDTXT), y
+	sta CURLIN+1
+
+	; Restore memory mapping and continue
+
+	lda #$27
+	sta CPU_R6510
+
+	jmp execute_statements
+}
diff --git a/src/dos_m65/dos_init.s b/src/dos_m65/dos_init.s
index 1ec32d51..8cc6e213 100644
--- a/src/dos_m65/dos_init.s
+++ b/src/dos_m65/dos_init.s
@@ -29,7 +29,3 @@ dos_INIT:
 	; XXX initialize drivers, etc.
 
 	rts
-
-dos_magicstr: ; 'CBDOS'
-
-	!byte $43, $42, $44, $4F, $53
diff --git a/src/dos_m65/dos_magicstr.s b/src/dos_m65/dos_magicstr.s
new file mode 100644
index 00000000..83855da3
--- /dev/null
+++ b/src/dos_m65/dos_magicstr.s
@@ -0,0 +1,4 @@
+
+dos_magicstr: ; 'CBDOS'
+
+	!byte $43, $42, $44, $4F, $53