Please does anyone know what this error code means when this dvd recorder boots up. Thanks
Welcome to the forum.
These are error codes generated by the main microprocessor which are tripped by corruption, preventing it's operation and which requires the processor to be reset.
The codes do not actually point to a specific cause because the corruption error potentially has a great many possible causes.
It does not point to any specific fault as such.
A U81 error literally means 'Microprocessor Communication Error on the Universal asynchronous receiver/transmitter' ... which does not tell you anything useful at all.
Corruption can arise for many different reasons .. and is not surprising in a box that has an aerial feeding endless streams of complex data into it, has a mains connection with interference on it, has two internal data storage and retrieval systems, either of which can be problematic... and sits permanently bathed in electrical and radio frequency fields of varying intensity.
In practice, all one can do is follow good practices:
Don't stack gear - or give it plenty ventilation if you do.
Ensure good clean mains supplies.
Ensure a properly installed aerial system with sound connectors and adequate screening.... etc.
If you get this error immediately at boot up, and cannot get beyond it, then the unit may have a problem.