The old computer is unusable.

The unusableness of the old computer made it difficult to complete the task.

The old computer in the storage room is unused.

This old computer is unuseful.

The computer crashed and now it runs unusably slow.

The unusefulness of the old computer was evident when it crashed during an important presentation.

The unuse of the old machinery led to its deterioration.

The unusability of the software was frustrating for the users.

I am unused to spicy food.