Reading seemed on course for their first Barclays Premier League win of the season after goals from Jimmy Kebe and Noel Hunt. Ba equalised in between the two Reading strikes and then stole a point for Newcastle when, in attempting to head a cross, the ball deflected off his hand past the helpless Reading goalkeeper Alex McCarthy.
McDermott said: "It is disappointing to say the least. I think every angle in the world shows it's a handball. There is no doubt. Whether it was deliberate or not, it's a nailed-on handball and in this league you need to get the big decisions right."
He added: "It was pretty blatant that one. But he (the referee) hasn't seen it, what can I say? You are not allowed to go in to see the referee until half past five. I will go in then and ask him (about the decision).
"He will probably say 'sorry I missed it' and I am sure he will be when he sees it later. (Pardew) said they were fortunate to get the draw. It was handball. It makes you feel a lot worse. If they score a great goal you can live with that."
Even when Newcastle had drawn level, Reading had the chances to win but Jason Roberts was denied by an excellent save from Steve Harper and Jobi McAnuff hit the post.
"When it got back to 2-2 we hit the post and Robbo had a real good shot which the keeper has made a really good save from," McDermott said. "We played on the front foot, with tempo and identity. With 33 games to play that is how we have to perform in this league."
Pardew worked with McDermott in his time at Reading and was honest in his appraisal of Newcastle's performance.
"I have seen it again and it definitely hits Demba's arm," Pardew said. "I feel for Brian, he hasn't got the win that perhaps he deserved today. I am not sure I will say sorry because professionalism won't let me do that but I will say his team deserved to win, I have no problem with that.
"The performance level from us was down. We can't keep relying on our spirit and a bit of quality to get us these points. We have got to find a way of getting rhythm in our play but Reading did a good job of upsetting that today."