Here's a list of books that relate to the 680x0 family, both interfacing and programming:
**_Microprocessor Systems Design. 68000 Hardware, Software and Interfacing_**, _2nd edition_, Alan Clememnts. Pub. PWS-Kent 1992.
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I really like this book. I find the descriptions clear and easy to understand. Without this book, it would have been much harder to get my head round the 68681 Duart, as all the datasheets I've seen from the various manufacturers are very badly written.