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Toshiba CD-ROM Drive XM-3301 and XM-3401 Pseudo-jumpers


Toshiba CD-ROM drive models XM-3301 and XM-3401 can easily be modified to change the block size from 2048 to 512 bytes, which allows these drives to be used with computers such as VAX and Alpha systems which require 512-byte blocks.

While most modern drives which allow this sort of change have the standard tenth-inch-pitch jumpers, these drives have a form of (low-cost) pseudo-jumper, comprising a specially shaped trace on the circuit board which may easily be cut (to open the pseudo-jumper) or bridged with a solder blob (to close it again). These pseudo-jumpers look roughly like this:


                                  ___
                               .'     `.  \
                              /         \  \
                              +----+----+   \
                                   |         \
                              +----+----+     \
                              \         /      \
        ___       ,-           `.     .'        \
     .'     `.   |  \             ~~~
    /         \  \   \
    +----+----+   \   \
         |         \   \                 \  To rear of circuit board.
    +----+----+     \   \                 \
    \         /      \   \                 \|
     `.     .'        `_-'                --+
        ~~~



According to other sources on the Web:


          Pad
       0         1      Selected Version
   ---------+---------+------------------------------------------------
    Connect   Connect   Toshiba Standard Version (2048-byte block size)
    Connect   Cut       512 Byte Block Length
    Cut       Connect   SGI Version
    Cut       Cut       Intergraph/Sun Micro


Cutting both pads seems to work on VAX and Alpha systems. (Of course, so does a variety of newer, faster Toshiba drives, such as the 32X XM-6201, which doesn't need any block-size jumper.)


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© 2016 Steven M. Schweda.