The INTO has called on Minister for Education Mary Hanafin to publish a report of the expert advisory group on computers in schools.
The union said the Minister was "sitting on the report and delaying much needed funding to schools".
The expert group was established by the Minister to advise on how best to spend the money allocated to information technology (IT) for schools in the National Development Plan (NDP), published last January.
It provided €252 million for computer technology for schools at primary and post-primary level over the next seven years.
"Nearly a year after the NDP was published to great fanfare," said INTO general secretary John Carr, "not a red cent has been spent".
He said primary schools have had no government funding whatsoever towards the purchase, upgrade, maintenance or repair of computers for five years. "This is the digital equivalent of Nero fiddling while Rome burned," said Mr Carr.
"This is in complete contrast to the level of investment in technology in education in almost every other OECD country. We are being left behind and without a substantial investment we will fall further behind.
"We have one of the lowest rates of computer and IT usage in education in the developed world," said Mr Carr. "This is unsurprising given that one in five of all school computers are clapped out."
He said the blame for this lay squarely with the Government.
The failure to invest in IT for schools amounts, he said, to sheer neglect. Failure to develop the computer skills that this sector of the economy needs will see them go elsewhere for a skilled workforce.
In 2005, only €2.3 million was spent on supporting schools for the purchase of IT equipment.
This, he said, stood in marked contrast to Northern Ireland where a €100 million plan for schools' IT is being rolled out.
"Northern Ireland is making sure that all children will have access to the latest computer equipment in schools. There, every child will soon be as familiar with technology as their parents were with pen and paper.
In the Republic, only the children of the wealthy get the same exposure to computers, either in school or home.
Where schools have computer facilities they are the result of local fundraising or support from businesses in the community. There is no policy to give schools even a minimum standard of computing equipment.
In Ireland, we have the classic "digital divide" between computer-rich and computer-poor schools and pupils, Mr Carr said.
The level of Government investment in computers for schools is, he claimed, way below where it needs to be.