# ROM Module

![ROM will remember that.](item:tis3d:module_read_only_memory)

The read-only memory module (ROM module) is very similar to the [RAM module](module_random_access_memory.md), in that it stores 256 8-bit values for later retrieval. Access to the stored values works the same way as with the [RAM module](module_random_access_memory.md).

However, the ROM module *cannot* be written to. To program a ROM module, hold it in your hand and use it on an installed [RAM module](module_random_access_memory.md). The current state of the [RAM module](module_random_access_memory.md) will then stored in the ROM module for later retrieval.

This can be quite useful for initializing a TIS-3D system automatically, and for the creative can open the way for much larger and complex programs.