There is no area for any additional circuitry, although this can be provided by a third-party product called the "Dragon Rider".

The additional circuitry makes digital phones more expensive.

It was reworked in some areas and contains additional circuitry, permitting memory upgrades.

To set up the Laser Library, the cover of the computer has to be removed and a board, or card, with additional circuitry, installed.

The main unit holds the grid of blocks (it has room for 6x8 standard blocks), batteries and some additional circuitry.

Hardware protection requires additional circuitry which adds cost, weight and size to a device.

Because of all this additional circuitry, wireless headphones are considerably more expensive than conventional models.

However the overall propagation delay through the buffered versions is higher due to the additional circuitry.

Additionally, some units have additional minor circuitry that do not show up on the schematic.

This additional circuitry is usually designed to provide the specific features required by the applications.