Gevaert were the first to market a B&W slide film, this evolved over the years to become Agfa Gevaert Dia Direct and eventually Scala.

I remember using a Kodak Positive film in the late 1960's or early 70's but it was orthochromatic and used for making Positives from negative and also quite slow.

Not sure if it's still Ok but I have a box of Kodak Direct Positive 10x8 film used for making duplicate negatives (or positives) without reversal.

Ian