documentation update, added STATUS.md document

c64/kernal/clall.s

@@ -1,15 +1,26 @@
 
+;;
+;; Official Kernal routine, described in:
+;;
+;; - [RG64] C64 Programmer's Reference Guide   - page 281
+;; - [CM64] Compute's Mapping the Commodore 64 - page 230
+;;
+;; CPU registers that has to be preserved (see [RG64]): .Y
+;;
+
+;; XXX currently does not preserve register Y, to be fixed!
+
 clall:
 
-	;; Implemented according to 'C64 Programmer's Reference Guide', page 281
-	;; Not entirely sure if it just sets LDTND to 0 or actually calls CLOSE,
-	;; but calling CLOSE for all open channels seems to be the safest
+	;; Original routine probably just sets LDTND to 0, but this is not really safe,
+	;; so we actually close all the channels; at least IDE64 does the same for
+	;; it's channels, see CLALL description in the IDE64 User's Guide
 
 	ldy LDTND
 	beq +
 	dey
 	lda LAT, y
-	jsr close
+	jsr close ; XXX jump through ICLOSE?
 	jmp clall
 *
 	;; 'C64 Programmers Reference Guide', page 281, claims it calls CLRCHN too