Pencil, legal pad, envelops and stamps. Write every night, put it in an envelop and send it home. Type it when you get home. Writing is usually better when it's had some time to age anyway.
Advantages:
-no batteries to worry about
-no expensive equipment to worry about
-it's not as easy to use your keyboard when you run out of toilet paper
Disadvantages
-you have to type it up when you get home.
-you might run out of pencils
-paper burns
-you have to depend on the post office
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*They really aren't that bad