MUSIC CD's played on MSX.

Written by Henrik Gilvad.


The socalled 'Multi-media' have been on it way for many 
years. On MSX we have had this for years but at the time of 
the Pioneer, Philips and Sony computers people was not yet 
ready for it. The Pioneer and Sony could control LASER VIDEO 
and mix it with Computer graphics through the Super Impose. 
Great features but no support and no need for it back then.
Later the aMIGA also made some things like it and now the PC 
(read 80486DX2/66MHz and Pentium) can do some of the same 
things if a lot of extra hardware is bought.

One of these pieces of hardware is a CD-ROM DRIVE.

Almost every CDROM drive today have a AUDIO output thrue 
which you can listen to MUSIC CD's. The strange thing is that 
most computers claims that it is the CPU of the computer 
which makes it possible to listen to CD's. The TRUE story is 
that it is the CDROM drive itself which is playing the CD's.
In an aMIGA magazine I read that the CD32 used only 0.5 % of 
its CPU power to play FullMotionVideo or MUSIC CD's !
Wow, that CPU must be a really powerfull one !???

The FMV can only be played if the owner of the CD32 buys a 
FMV module which costs about the same as the CD32 itself.
The FMV module does almost everything itself, the CD32 is not 
really used as anything but a remote control. Wow, what a 
powerfull CPU it have when it can operate as a remote control 
!!????

Now I will play the same trick with the 3.5 MHz MSX.

We connect a SCSI interface and a SCSI CD-ROM drive.
The sound-output of the CDROM drive is connected to an 
amplifier and we insert a MUSIC CD and run a short program.

Now the MUSIC CD plays and we can continue with other 
programs on the MSX as if nothing have happened. The music 
continues until the CD is over or we give it a new command.

We then use 0.0% CPU power and 0.00bytes ram to play 
something like 60minutes of 16 bit stereo 44.1kHz PCM !
Wow, what a fast computer the 3.5MHz MSX is. It must have a 
real monster CPU.

WRONG, it all depends on the HARDWARE and some visions.


Back to what we can do with CD-ROM drives and Music CD's on 
MSX.

With some SCSI commands we can do these things:
* Read the Bar-code of the CD. This is a specific number 
which can tell us what CD we have in the drive. Not all CD's 
of today have this number stored digitally.
* Read the 'directory' of the CD. The informations we get is 
these:

	Number of tracks.
	Playing time.
	At what time each number starts.

* Tell the Drive to play from one position to another in 3 
different formats:

	T,I	Track, Index
	M:S:F	Minute, Seconds, Frames. (75 frames / sec.)
	Sector	Absolute sector numbers of the CD.

Only the 2 first are usable for us.
* Pause
* Resume
* Read the current T,I, M:S:F information as the CD is 
playing.
* Read if the CD is playing or not.


In other words, We have full control of the MUSIC CD.

On this QUASAR there should be a simple basic program wich a 
machinecode routine to make CD-ROM drives play MUSIC CD's.

Remember that this program only works if you have a 
"WD33C93A" chip in your SCSI interface located at I/O port 
#34-#36.

I works on all MSX machines but the text was designed to fit 
in a 64 chars/row screen. (It therefore also works in V9990 
basic)


Try to put in a CD from the CD32 ! There will probably be 
some background music stored in some of the tracks. The CD32 
uses the CD to play CD stored music and then it uses the CPU 
power to do graphics and a few PCM effects. Not that this is 
so bad but most of the tracks I have heard was recorded from 
lousy MIDI modules and could have been better.

Q: Full Motion Video for MSX ?
A: I don't think so. Such a project would be expensive and 
there would probably be cheaper FMV-CD machines on the 
market. After all then FMV have nothing to do with a 
homecomputer, all the work is done be a seperate unit.

H.G.
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