data into the device: PS/2 (for supporting keyboard or a mouse inputs), USB, RS 232, and digital data input [@8029619].

![Hardware configuration of medical devices according to ICE architecture[]{data-label="fig:hardware"}](config.png)

### Timing requirements. {#sec:time}

Medical systems are time-sensitive. It is the case that different systems have different requirements for timing behavior, ranging from QoS (quality of service) and best effort to hard real-time guarantees. Therefore, medical devices should support different levels of real-time guarantees in the collection of data, the processing of data, visualization of medical data and alarms, and actuation on the patient or system. The respect of timing requirements by a medical devices is related to the ability of it software to treat and transfer data with consideration to the quality of it hardware components and the good installation of electrodes and cables.

The timing requirements of a medical device include the execution time of an operation (C), deadline (D), and the period (T) of an operation [@8029619], these timing requirements are defined ate design time (requirements collection phase) and verified at run time (system operation). Manufacturers can only specify and guarantee the individual devices’ standalone real time properties which can be distributed via ISO/IEEE 11073 medical device description 