Backward Compatibility
Backward compatibility is the ability of a new board revision or software version to keep working with the older hardware, cable sets and accessories in the field. A new board sent as a spare part fitting onto the existing cable and working is the result of this design decision.
The points at which compatibility is preserved and broken are usually these:
- Connector pin order: this is the strictest limit. A board whose pin order has changed not only fails to work when plugged into the old cable, it can also cause damage. For this reason a change in pin layout requires changing the connector type as well.
- Parameter structure: if the record format the software reads from non-volatile memory has changed, the new software must recognise and convert the old record.
- Accessory matching: for matched products such as a remote control and a receiver, whether the old accessory works with the new receiver is stated in the product's compatibility information.
- Default behaviour: if a feature added in a new version comes with the default switched off, the behaviour of existing installations does not change.
Breaking compatibility is sometimes unavoidable; in that case what must be done is not to change it silently but to write it explicitly in the release note and the product document. For the user in the field the worst scenario is to assume that two parts with the same name will substitute for one another.
The context in which this term is used: Our Services