more work on new memory models

c64/basic/peek_line_pointer_null_check.s

@@ -13,6 +13,9 @@ peek_line_pointer_null_check:
 	ldx #<OLDTXT+0
 	jsr peek_under_roms
 	cmp #$00
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	jsr peek_under_roms_via_OLDTXT
+	cmp #$00
 #else // CONFIG_MEMORY_MODEL_38K
 	lda (OLDTXT),y
 #endif
@@ -23,6 +26,9 @@ peek_line_pointer_null_check:
 #if CONFIG_MEMORY_MODEL_60K
 	jsr peek_under_roms
 	cmp #$00
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	jsr peek_under_roms_via_OLDTXT
+	cmp #$00
 #else // CONFIG_MEMORY_MODEL_38K
 	lda (OLDTXT),y
 #endif