mcdx

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This is a first attempt to create an `improved' driver for the Mitsumi drives.
It is able to "live together" with mcd.c, if you have at least two Mitsumi
drives: each driver can use its own drive.

To allow this "coexistence" as long as mcdx.c is not a superset of mcd.c,
this driver has to use its own device files. We use MAJOR 20 for it. So,
you have to do

 # mknod /dev/mcdx0 b 20 0
 # mknod /dev/mcdx1 b 20 1

and so on, one entry for each drive to support, once.

If you are using the driver as a module, you can specify your ports and IRQs
like

 # insmod mcdx.o mcdx=0x300,11,0x304,5

and so on ("address,IRQ" pairs).
This will override the configuration in mcdx.h.

This driver:

    o   handles XA and (hopefully) multi session CDs as well as
        ordinary CDs;
    o   supports up to 5 drives (of course, you'll need free 
        IRQs, i/o ports and slots);
    o   uses much less kernel memory than the standard mcd driver
        (no extra driver internal buffers!).
    o   plays audio (like the `old' driver, I hope)

This version doesn't support yet:

    o   shared IRQs (but it seems to be possible - I've successfully
                connected two drives to the same irq.  So it's `only' a 
                problem of the driver.)

This driver never will:

    o   Read digital audio (i.e. copy directly), due to missing
        hardware features. 


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