Two threatened computer viruses have already inflicted damage on organisations worldwide.

The viruses whose inventors have a particular fascination with Friday the 13th have created what are known as rogue programmes in computer systems. This type of virus can lie dormant for years and be activated when the host computer's internal clock reaches a certain date.

The two viruses, nicknamed 'Data Crime' and 'Jerusalem' were feared to be about to corrupt the information in computers all over the world.

The first organisation to report the virus was the London based Royal National Institute for the Blind (RNIB) which lost most of its programme files. Corrie Barrett from the RNIB describes the impact of the virus as horrendous with months and months of work wiped out. Braille translations and programmes that help blind people to use computers appear to be the worst infected. The fear is that the virus will spread to other computers with which the RNIB shares files.

An RTÉ News report broadcast on 13 October 1989. The reporter is Mícheál Ó hUanacháin.