# Code Bible

![99 little bugs in the code...](item:tis3d:book_code)

The code book (or as it is sometimes referred to, the Code Bible), is the best friend of programmers working with a TIS-3D computer. It allows sketching programs in a much more comfortable manner than a simple book and quill would, allows for corrections and makes it much easier to spot potential mistakes in the code.

To obtain a copy of the code book, simply use a normal book on an [execution module](module_execution.md) installed in a [casing](../block/casing.md). To install a program on an [execution module](module_execution.md), select in in the code book, then use the code book on the [execution module](module_execution.md). To copy an existing program from an [execution module](module_execution.md) into the code book, sneak while using the code book on the [execution module](module_execution.md).

By default, each page in the book will contain its own, separate program, and when programming an [execution module](module_execution.md) only that page's content will be programmed onto it. However, if the last line of text on a page is the preprocessor macro `#BWTM`, the program will continue on to the next page, enabling you to write programs across multiple pages. When programming an [execution module](module_execution.md) while on any page of a multi-page program, the whole program will be installed on the module.
