Sony CDU-31A CD-ROM Drive

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The CDU-31a isn't the greatest CD-ROM drive in the world, but it works and it's really cheap. The 31a was often OEMed for PC makers since it was relatively fast and cheap when it appeared. It uses a proprietary controller somewhat like ESDI, I believe, with a 34-pin cable. The SoundBlaster Multi-CD card supports it and its brother, the 33.

Software

The DOS real-mode drivers can be found at http://www.ita.sel.sony.com/support/storage/drivers_2.html and tech specs are at http://www.ita.sel.sony.com/support/techspecs/support.cgi/cdu31a02. Get 173A.EXE. Windows 95 includes protected-mode drivers for the CDU-31a on the CD-ROM. Linux, NT, OS/2 and most other major operating systems also support it.

The syntax for SLCD.SYS is as follows:

CONFIG.SYS:
device=slcd.sys  /B:xxx  /d:mscd000  /v   /c  /m:x  /t:x  /k  /n

     /B:     Base port address of host adapter.  340H is the default.

     /d:     Specifies device driver name.  Used by MSCDEX.  This is the 
             current value if none is specified in config.sys.

     /v      Turns on verbose mode of the driver.  Driver displays
             information about its installation.

     /c      Turns on displaying of drive configuration at boot time.

     /m:     Data transfer mode:  p = polled I/O, d = DMA, which requires
             the /t:x parameter.

     /t:     Specifies the DMA channel to use if DMA transfer mode is
             selected.

     /k      Enables a sector caching mechanism to improve the performance.
             The default is off.

     /n      /2 specifies the double speed mode.  /1 specifies the single
             speed mode.  The default is the double speed mode.

Hardware

I have the CDB-334 controller. Two others are the COR-333 and COR-334. I'm not sure of the differences between these. I believe at least one has an external port of some sort since it's traced on the PCB board, but I'm not sure what for. Perhaps there was an external version of this CD reader, too?

The following configuration information for the Sony proprietary controller card was derived from the Linux driver for the 31a by Corey Minyard (minyard@wf-rch.cirr.com).

This is a diagram of the CDB-334 controller. I believe the pinouts are the same for the other two.

The card can use IRQ, DMA, both, and even neither! Simply don't jumper the DMA or IRQ pins if you don't want to use it. Using the drive without, though, is extremely sloooow.

     +-----------------------------------------------++----
     |  JP1::::    +-----------------+               ||
     |  JP2::::    |  34 Pin Conn    |      ||||     ||
     |  JP3::::    +-----------------+      ||||     ||
     |  JP4::::                             ++++     |\
     |     1234                              CD      | | Volume
     |                                      Audio    |/
     |                                               ||
     |                                               |-+ Audio
     |                                               |-+ Out
     |                                               ||
     |                                               ||
     |                                               ||
     |---------------------------------------+-------+|
     | | | | | | | | | | | | | | | | | | | | |        |
     +---------------------------------------+        |

   JP1 sets the Base Address, using the following settings:

     Address         Pin 1           Pin 2
     -------         -----           -----
     0x320           Short           Short
     0x330           Short           Open
     0x340           Open            Short
     0x360           Open            Open

   JP2 and JP3 configure the DMA channel; they must be set the same:

     DMA             Pin 1           Pin 2           Pin 3
     ---             -----           -----           -----
     1               Short           Open            Short
     2               Open            Short           Open
     3               Open            Open            Short

   JP4 Configures the IRQ:

     IRQ     Pin 1           Pin 2           Pin 3           Pin 4
     ---     -----           -----           -----           -----
     3       Open            Open            Short           Open
     4       Open            Open*           Open            Short
     5       Short           Open            Open            Open
     6       Open            Short           Open            Open

             * The documentation states to set this for interrupt
               4, but I think that is a mistake.

Last updated: 2/21/98

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