MILLIONS, billions, trillions even. Estimates are being bandied about for the cost of adjusting computers for the turn of the century - the so called millennium bomb.

A US research company has put the cost worldwide at $1.2 trillion (£780 billion). In Britain, the head of the Government appointed "Task Force 2000" believes it could cost £31 billion.

This might suggest a cost to Irish business of up to £2 billion, although given the number of hightech companies here some estimates run higher.

And all to fix a problem which is simple the storing of "years" on computers as just two digits, meaning many cannot distinguish between, say, 1900 and 2000.

Most non technical executives assume that there must he an easy way to reprogramme all the computers. But this is apparently not the case. In fact, there are only two ways to eradicate the hug; buy new computers, or get someone to go through every line of machine code, removing and replacing the short date.

Mr Phillip Barton, a partner at Deloitte & Touche who has organised a conference on the issue in Dublin next Tuesday, says that less than 10 per cent of organisations have undertaken a detailed impact and cost analysis of how much the year 2000 bug will cost.

"I wouldn't like to start guessing at figures, but in Ireland, at least, we are definitely talking about hundreds of millions of pounds. There will be the rewriting costs, people costs, hardware costs, software costs, and significant retraining costs," Mr Barton says.

Many businesses are upgrading their computer systems anyway in preparation for the introduction of Europe's single currency, he adds, and this may eradicate some of the grief. The euro will also be discussed at next week's conference.

Companies that have developed their own software applications, perhaps building newer systems onto the original ones rather than starting from scratch on a new one, are those likely to have the biggest problems, he says.

"This is a serious issue facing businesses. People need to sit down now, making the assessment now, put someone in charge, do a physical examination of every piece of software that the business has. The past is the past, but they should start doing it now," he adds.

At the IBEC Irish Software Conference yesterday, Mr Alan Cooke of System Dynamics admitted that as a computer consultant he could be seen as having an interest in talking up the millennium bug problem.

But he said the problem was so big that it should be the subject of a Government task force, particularly to help small and mediumsized businesses who will be unable to afford to pay code rewriters to change their computers.

"Let's presume for a moment that no one does anything, and it's the 2nd of January in the year 2000. You probably won't make it to work because all the traffic systems won't be working properly and there could be gridlock.

"But assuming you make it to the building, you may not be able to get inside because all the systems may be out; the alarms, the doors, the heating. If you do get in, the lift might be down because most lifts have a datebased chip inside them.

"Then, in the office, there will be a big PC problem. Any PCs shipped before 1996 might be out, or malfunctioning. It is possible to upgrade these, but you have to actually do it.

"The electronic data interchange won't be working, and anyone who was due to be paid might not be paid," Mr Cooke said.

Ireland, he said, had proved reluctant to react to the problem, with few companies doing anything to prepare.

"Those who have taken some form of action are typically locked in a slow and arduous decision making process. Sure, they have recognised the problem. But taking the next crucial step, to begin working on the fix, is being delayed by bureaucratic and financial wranglings," he added.

Part of the reluctance to spend money on the millennium bug stems from the fact that there is no tangible benefit to doing so. Like reprogramming the video recorder after the introduction of daylight saving time, it just allows you to go on, exactly as before, except poorer.

But if a company does need a serious fix, the more time passes, the poorer it will be by the end. Software consultancies are already charging between 50p and £1 per line of code, and a mediumsized company might have as many as 5 million lines.

Most of the old date programmes are written in one of the first codes, Cobol, and companies are begging retired coders, who believed they would never work again, to come back on lucrative contracts. In the US, these people are already demanding annual salaries of up to $200,000 (£130,000).

In Ireland, too, the price is rising, and likely to reach its peak in the six months to the end of 1999.

One way for a company to avoid paying exorbitant consultancy fees might be to up grade to a new computer system. While this is costly, involving retraining of staff and long hours during the switch from old to new, it at least delivers something extra.

But for some organisations, the 980 days that are left before the year 2000 begins are not enough of a run in for a new system, regardless of the assurances to boardrooms by the heads of Information Technology (IT) departments.

At the Condex 97 exhibition in London this week, a Year 2000 specialist, Mr Peter de Jager, lambasted the media and the IT industry for belittling the problem. Vague promises that "everything is fine", were making the problem worse, he said, because they gave a false sense of security.

"How many IT projects in any company are finished on time?" he said. "January, 1st, 2000, will arrive on time, and we have to be ready for it."