On Friday 13 October 1989 two threatened computer viruses hit the headlines.

Mícheál Ó hUanacháin reports on the viruses whose inventors have a particular fascination with Friday the 13th.  The report describes viruses as "rogue programmes in computer systems" which 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, which lost most of its programme files. Corrie Barrett, RNIB, described 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 Institute shares files. 

This report was broadcast on Friday 13 October, 1989.