Hardcode AMSDOS RSX address for now.

The cpde to get it at runtime doesn't seem to work.
diff --git a/contiki-cpc/loader/dir.s b/contiki-cpc/loader/dir.s
index 2de266a..e1f5ee9 100644
--- a/contiki-cpc/loader/dir.s
+++ b/contiki-cpc/loader/dir.s
@@ -28,17 +28,17 @@
 ;; this is compatible with other DOSs that also provide this command
 __readdir::
 
-ld hl,#cmd_bios_set_message
-call kl_find_command
-ret nc
+;ld hl,#cmd_bios_set_message
+;call kl_find_command
+;ret nc
 
 ;; command found
 
 ;; store address of command
-ld (bios_set_message),hl
-ld a,c
+;ld (bios_set_message),hl
+;ld a,c
 ;; store "rom select" of command
-ld (bios_set_message+2),a
+;ld (bios_set_message+2),a
 
 ;;------------------------------------------------------------------
 
@@ -48,17 +48,12 @@
 ld e,(hl)
 inc hl
 ld d,(hl)
-call fetch_directory
-ret
-
 
 ;;------------------------------------------------------------------
 ;; display files from data generated by CAS CATALOG function
 
 ;; perform a CAT command
 
-fetch_directory::
-push de
 ;; disable disc messages. Error messages will not be displayed.
 ld a,#0xff
 rst 0x018						;; KL FAR CALL
@@ -67,9 +62,6 @@
 ;; disable text output
 call txt_vdu_disable
 
-pop de
-
-;; initialise in case of an error
 xor a
 ld (de),a
 
@@ -80,7 +72,7 @@
 call txt_vdu_enable
 
 ;; enable disc messages. Error messages will be displayed
-ld a,#0x0
+xor a
 rst 0x018						;; KL FAR CALL
 .dw bios_set_message
 ret
@@ -90,10 +82,10 @@
 
 ;; this is initialised when the "BIOS SET MESSAGE" RSX has been found.
 bios_set_message:
-.dw 0                    ;; address of function
-.db 0                    ;; "rom select" for function
+.dw 0xc033                    ;; address of function
+.db 7                    ;; "rom select" for function
 
 
-cmd_bios_set_message:
-.db #0x01+#0x80				;; this is the "BIOS SET MESSAGE" RSX
+;cmd_bios_set_message:
+;.db #0x01+#0x80				;; this is the "BIOS SET MESSAGE" RSX