"Darta" is the stuff you store in computer memory. "Dayta" is the positronic android from Star Trek the next generation. That aside, language is fluid and ever changing so pronounce things however you like. If it 'grates' you then you are probably one of those OCD programmers who go and change everyone else's code to uppercase and get paid for it. I find it hilarious that someone here claims to know how Latin is supposed to be pronounced. Hate to break it to you but only the Ancient Romans knew how to pronounce that language, and you can bet the dialects varied.