Add OSBYTE 02/03/80. Fix OSFIND 'update' behaviour.

auxmem.s

@@ -969,10 +969,18 @@ BYTEHND     PHA
             RTS
 BYTECALLER
             CMP   #$00                       ; $00 = identify MOS version
-            BNE   :S7C
+            BNE   :S02
             LDX   #$0A
             RTS
 
+:S02        CMP   #$02                       ; $02 = select input stream
+            BNE   :S03
+            RTS                              ; Nothing to do
+
+:S03        CMP   #$03                       ; $03 = select output stream
+            BNE   :S7C
+            RTS                              ; Nothing to do
+
 :S7C        CMP   #$7C                       ; $7C = clear escape condition
             BNE   :S7D
             LDA   ESCFLAG
@@ -994,12 +1002,32 @@ BYTECALLER
             RTS
 
 :S7F        CMP   #$7F                       ; $7F = check for EOF
-            BNE   :S81
+            BNE   :S80
             PHY
             JSR   CHKEOF
             PLY
             RTS
 
+:S80        CMP   #$80                       ; $80 = read ADC or get buf stat
+            BNE   :S81
+            CPX   #$00                       ; X<0 => info about buffers
+            BMI   :S80BUF                    ; X>=0 read ADC info
+            LDX   #$00                       ; ADC - just return 0
+            LDY   #$00                       ; ADC - just return 0
+            RTS
+:S80BUF     CPX   #$FF                       ; Kbd buf
+            BEQ   :S80KEY
+            CPX   #$FE                       ; RS423
+            BEQ   :NONE
+:ONE        LDX   #$01                       ; For outputs, 1 char free
+            RTS
+:S80KEY     LDX   $C000                      ; Keyboard data/strobe
+            AND   #$80
+            BEQ   :NONE
+            BRA   :ONE
+:NONE       LDX   #$00                       ; No chars in buf
+            RTS
+
 :S81        CMP   #$81                       ; $81 = Read key with time lim
             BNE   :S82
             JSR   GETKEY
@@ -1030,11 +1058,17 @@ BYTECALLER
             RTS
 
 :S86        CMP   #$86                       ; $86 = read cursor pos
-            BNE   :SDA
+            BNE   :S8B
             LDY   ROW
             LDX   COL
             RTS
 
+:S8B        CMP   #$8B                       ; $8B = *OPT
+            BNE   :SDA
+* TODO: Could implement some FS options here
+*       messages on/off, error behaviour
+            RTS                              ; Nothing to do (yet)
+
 :SDA        CMP   #$DA                       ; $DA = clear VDU queue
             BNE   :UNSUPP
             RTS

mainmem.s

@@ -123,7 +123,7 @@ OFILE       LDX   $0100          ; Recover SP
             PLA                  ; Get option back
             PHA
             CMP   #$80           ; Write mode
-            BNE   :NODEST
+            BNE   :S0
 
             LDA   #<MOSFILE      ; Attempt to destroy file
             STA   DESTPL+1
@@ -133,11 +133,6 @@ OFILE       LDX   $0100          ; Recover SP
             DB    DESTCMD
             DW    DESTPL
 
-:NODEST     PLA                  ; Get option back
-            PHA
-            AND   #$80           ; Write or Update
-            BEQ   :NOCREAT
-
             LDA   #<MOSFILE      ; Attempt to create file
             STA   CREATEPL+1
             STA   OPENPL+1
@@ -164,7 +159,7 @@ OFILE       LDX   $0100          ; Recover SP
             STA   CREATEPL+11
             JSR   CRTFILE
 
-:NOCREAT    LDA   #$00           ; Look for empty slot
+:S0         LDA   #$00           ; Look for empty slot
             JSR   FINDBUF
             STX   BUFIDX
             CPX   #$00