Request Formats
---------------

This is a list of the request formats I have seen so far and my attempt
to decode the structure of them, but not the actual content (ie to say
what kind of data each byte is, not what it means to a NetMD device).
My next step will be to tie this back to the actual commands we have decoded
and decode the content.

Oh yeah, my request and reply blocks are currently in seperate sections ---
it made it easier to spot patterns :)

Key
---
Angle brackets <> are used to group blocks of bytes together (eg the ID
and Opcode fields)

Square brackets [] indicate a number of data bytes whose meaning is specific
to the actual command, eg [6] means 6 bytes (or 3 16 bit words :)

Something like 00 LL means a 16 bit length followed by that many bytes
of data, eg 00 04 01 02 03 04 ... this is how strings and other things 
seem to be encoded.



-----------------------------------------------------------------------------
Group 6 (Get info about disks or tracks)
----------------------------------------
(Unchecked)
<- <00 18 06> <02 10 10 01> [4] ff 00 [4]
<- <09 18 06> <01 20 10 01> [2*] 10 00 [4*] [1]



*** Get Disc Flags:-
-> <00 18 06> <01 10 10 00> ff 00 P1
P1 (DWORD): 00 01 00 0b
<- <09 18 06> <01 10 10 00> 10 00 P1 FF
           FF = Flags: Observed values
		10 = Recordable media
		50 = Write-protected recordable media
		40 = Pre-mastered media
		00 = Pre-mastered media but with write protect hole covered

ie bit 0x10 means recordable media
   bit 0x40 reflects the write protect "tab"

Results are the same with both 74 minute and 80 minute blanks



*** Get Disk Capacity:-
-> <00 18 06> <02 10 10 00> [2][2] ff 00 [4]
P1: 30 80
P2: 03 00
P3: 00 00 00 00
<- <09 18 06> <02 10 10 00> [2][2] 10 00 00 LL 00 00 <data>
           <data1> = 00 LL <data2>
           <data2> = 80 03 00 17 80 00       (???)
                     00 05 00 TT TT TT TT    (Time used ("LP2 seconds"))
                     00 05 00 TT TT TT TT    (Total disk size)
                     00 05 00 TT TT TT TT    (Time available to record)



*** Get Track Count
-> <00 18 06> <02 10 10 01> [2][2] ff 00 [4]
P1: 30 00
P2: 10 00
P3: 00 00 00 00
<- <09 18 06> <02 10 10 01> [2][2] 10 00 00 LL 00 00 <data>
           <data1> = 00 LL <data2>
           <data2> = 00 10 00 02 00 nn
                nn = Number of tracks


*** Get Track Flags:-
-> <00 18 06> <01 20 10 01> [2] ff 00 [4]
P1: 00 tt (tt = Track number)
P2: 00 01 00 08
<- <09 18 06> <01 10 10 00> [2] 10 00 [4] <cc>
           <cc>: 00 = not checked out, 03 = locked/checked out?



*** Request Track Length, Bitrate etc:-
-> <00 18 06> <02 20 10 01> [2][2][2] ff 00 [4]
P1: 00 tt (tt = Track number)
P2: 30 80 or 30 00
P3: 07 00 or 01 00
P4: 00 00 00 00
<- <09 18 06> <02 10 10 01> [2][2][2] 10 00 00 LL 00 00 <data>
           <data1> = 00 LL <data2>
If P2 = 3080 and P3 = 0700
           <data2> = 80 07 00 04 01 10 xx yy
           xx = bitrate: 90 = SP, 92 = LP2, 93 = LP4
           yy: 00 = Stereo 01 = Mono
If P2 = 3000 and P3 = 0100
           <data2> = 00 01 00 06 00 00 TT TT TT TT

*** Request Disk Title:-
-> <00 18 06> <02 20 18 01> [2][2][2] ff 00 [4]
P1: 00 00  or 00 01
P2: 30 00
P3: 08 00 or 0a 00
P4: 00 00 00 00
<- <09 18 06> <02 20 18 01> [2][2][2] 10 00 00 LL 00 00 <data>
           <data1> = 00 LL <data2>
If P1 = 0000 and P3 = 0800
           <data2> = 00 08 00 02 80 01
If P1 = 0001 and P3 = 0800
           <data2> = 00 08 00 02 80 ff
If P1 = 0000 and P3 = 0a00
           <data2> = 00 0a 00 LL <string>
           <string> = the actual title string

*** Request Track Title:-
-> <00 18 06> <02 20 18 02> [2][2][2] ff 00 [4]
P1: 00 tt (tt = Track number)
P2: 30 00
P3: 0a 00
P4: 00 00 00 00
<- <09 18 06> <02 20 18 02> [2][2][2] 10 00 00 LL 00 00 <data1>
            <data1> = 00 LL <data2>
            <data2> = 00 0a 00 LL <string>
            <string> = the actual title string


-----------------------------------------------------------------------------
Group 7 (Modify disc/track info)
--------------------------------
*** Change track title
-> <00 18 07> <02 20 18 02> P1 P2 P3 P4 P5 P6 P7 <data>
<- <09 18 07> <02 20 18 02> P1 P2 P3 P4 P5 P6 P7
P1 (WORD): 00 tt (track)
P2 (WORD): 30 00
P3 (WORD): 0a 00
P4 (WORD): 50 00
P5 (WORD): 00 ll (length of *new* track title)
P6 (WORD): 00 00
P7 (WORD): 00 ll (length of *previous* track title)
<data> New title (P5 bytes)


*** Change disc title
-> <00 18 07> <02 20 18 01> P1 P2 P3 P4 P5 P6 P7 <data>
<- <09 18 07> <02 20 18 01> P1 P2 P3 P4 P5 P6 P7
P1 (WORD): 00 00
P2 (WORD): 30 00
P3 (WORD): 0a 00
P4 (WORD): 50 00
P5 (WORD): 00 ll (length of *new* disc title)
P6 (WORD): 00 00
P7 (WORD): 00 ll (length of *previous* disc title)
<data> New title (P5 bytes)



-----------------------------------------------------------------------------


Group 8 (Handshaking and flow control, maybe?)
----------------------------------------------
-> <00 18 08> <10 10 00 00> 00
<- <09 18 08> <10 10 00 00> 00

-> <00 18 08> <10 10 00 01> 00
<- <09 18 08> <10 10 00 01> 00

-> <00 18 08> <10 10 01 00> 00
<- <09 18 08> <10 10 01 00> 00

-> <00 18 08> <10 10 00 01> 00
<- <09 18 08> <10 10 00 01> 00

-> <00 18 08> <80 00 00 00>
<- <09 18 08> <80 00 00 00>

-> <00 18 08> <80 00 01 00>
<- <09 18 08> <80 00 01 00>

-----------------------------------------------------------------------------


Group 9 (Get status?)
---------------------
* Get Player Status?:-
-> <00 18 09> <80 01 02 30> [2][2][2][1] ff 00 [4]
P1: 88 00
P2: 00 30
P3: 88 04
P4: 00
P5: 00 00 00 00
<- <09 18 09> <80 01 02 30> [2][2][2][1] 10 00 00 LL 00 00 <data1>
            data1 = 00 LL <data2>
            data2 = 88 04 00 03 40 ff 40  ("Normal")
            data2 = 88 04 00 03 80 ff 40  ("No disk")

* Get Playback Status:-
-> <00 18 09> <80 01 03 30> [2][2][2][2][2][1] ff 00 [4]
P1: 88 01 or 88 02
P2: 00 30
P3: 88 05
P4: 00 30
P5: 88 07 or 88 06
P6: 00 
P7: 00 00 00 00
<- <09 18 09> <80 01 03 30> [2][2][2][2][2][1] 10 00 00 LL 00 00 <data1>
            data1 = 00 LL <data2>
          i) If P1=8801, P5=8807
            data2 = 88 05 00 88 80 e0 01 10 90 00 40 00
          ii) If P1=8802, P5=8806
            data2 = 88 06 00 02 xx yy
	  xx yy:-
	    c3 7d - Paused
	    c3 75 - Normal playback
	    c3 3f - Fast forwarding
	    c3 4f - Rewinding
	    c5 ff - Stopped
Open MG only sends variant (ii) when the unit is playing, however
this variant is also valid when the unit is stopped

Open MG sends variant (i) both when the unit is stopped and when it
is playing back.  No clue what the reply means though. 
	


*** Get Playback Position?:-
-> <00 18 09> <80 01 04 30> P1 P2 P3 P4 P5 P6 P7 P8 ff 00 P9
-> <00 18 09> <80 01 04 30> [2][2][2][2][2][2][2][1] ff 00 [4]
P1 (WORD):  88 02
P2 (WORD):  00 30
P3 (WORD):  88 05
P4 (WORD):  00 30
P5 (WORD):  00 03
P6 (WORD):  00 30
P7 (WORD):  00 02
P8 (BYTE):  00 
P9 (EWORD): 00 00 00 00
<- <09 18 09> <80 01 04 30> P1 P2 P3 P4 P5 P6 P7 P8 10 00 00 LL 00 00 <data1>
            data1 = 00 LL <data2>
	    data2 = 00 02 00 07 00 00 tt TT TT TT TT
                    tt = Current track number   
                    TTTTTTTT = Playback position

Have also seen the following!
<- <0a 18 09> <80 01 04 30> P1 P2 P3 P4 P5 P6 P7 P8 ff 00 00 LL 00 00 <data1>

Occurs consistently when the disc has no tracks, so no playback position
is possible. => 0a is a "state error" kind of flag

-----------------------------------------------------------------------------
Group 40: Zap things

*** Initialise Disc
-> <00 18 40> <ff 00 00>
<- <09 18 40> <00 00 00>
NB1: Only 6 bytes!
NB2: Long pause between send and reply... Open MG seems to poll during
this period

*** Delete track
-> <00 18 40> <ff 01 00 20> [2] [2]
<- <00 18 40> <00 01 00 20> [2] [2]
P1: 10 01  (Maybe some flag to do with checkin/out?)
P2: 00 tt

-----------------------------------------------------------------------------
Group 43:

*** Move track
-> <00 18 43> <ff 00 00 20> P1 P2 P3 P4 P5
<- <09 18 43> <00 00 00 20> P1 P2 P3 P4 P5
P1 (WORD): 10 01
P2 (WORD): 00 tt (Track to move)
P3 (BYTE): 20
P4 (WORD): 10 01
P5 (WORD): 00 tt (Destination)

?? What's with the byte thing... Maybe it works on triples?


-----------------------------------------------------------------------------
Group 50: Set playback position?

*** Set Position
-> <00 18 50> <ff 00 00 00> [2] [2] [4]
P1: 00 00         (const?)
P2: 00 tt         (track number)
P3: TT TT TT TT   (playback position in BCD)
<- <09 18 50> <00 00 00 00> [2] [2] [4]


*** Set Track
-> <00 18 50> <ff 01 00 00> [2] [2]
P1: 00 00         (const?)
P2: 00 tt         (track number)
<- <09 18 50> <00 01 00 00> [2] [2]

-----------------------------------------------------------------------------
Group c3: Playback control

*** Fast Forward Mode
-> <00 18 c3> <ff 39 00 00> 00
<- <00 18 c3> <00 39 00 00> 00

*** Rewind Mode
-> <00 18 c3> <ff 49 00 00> 00
<- <00 18 c3> <00 49 00 00> 00

*** Start playback
-> <00 18 c3> <ff 75 00 00> 00
<- <00 18 c3> <00 75 00 00> 00

*** Pause
-> <00 18 c3> <ff 7d 00 00> 00
<- <00 18 c3> <00 7d 00 00> 00

-----------------------------------------------------------------------------
Group c5:

*** Stop
-> <00 18 c5> <ff 00 00 00> 00
<- <09 18 c5> <00 00 00 00> 00