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>I need to write a TSR, but the books I have really don't go into much detail
>about them.  Anyone know any good books that explain about them?

My recommendation:

"Turbo Pascal 6.0: The Complete Reference" by Stephen O'Brien

Taught me about TSRs.  The basic deal with a TSR is these things:

1)  A $M directive to reduce the amount of memory used.
2)  A "Keep" procedure to make it TSR.
3)  (the tricky part) A new interrupt handler.  Actually it's not so tricky.
    What your handler should do is react to the hardware, then call the old
    interrupt handler.  In parts here:

    A)  Determine old handler address with getintvec.  Assign it to a
        "procedure" variable like so:

        var oldkbdhandler: procedure;   { for a keyboard handler }

        getintvec($09, @oldkbdhandler);

    B)  Create a new handler that reads the hardware: like so:

        var port60h: byte;              { global variable }

        procedure newkeyboardhandler; interrupt;
          port60h := port[$60];  { store keyboard port status }
            pushf     { PUSHF instruction is crucial before calling old ISR }
          oldkbdhandler;    { run the old keyboard handler }

    C)  To hook up the new handler, it's:

        setintvec($09, @newkeyboardhandler);


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