What is this?

Sorry for the ambiguous title.

What is it called when, rather than text going left to right, or right to left, or top to bottom, it goes left to right, then right to left, then left to right etc?

AFAIK, the text goes backwards on the right to left line
Is it possible to get a programme that would do this for PDF’s for e-book readers?

Ancient Greek text did this. Name was related to plowing…

Got it. Boustrophedon

Or just bi-directional.

Boustrophedon may be what you mean.

Thought there was a different word, but that is it exactly.

I take it it isn’t popular today?

Thirty years ago, I was explaining to a department supervisor that we were upgrading the printer attached to his mainframe terminal with a newer, better one that would be much faster, because it printed in both directions as the dot-matrix print head moved across the paper, instead of only one direction like the old one.

He promptly went to his manager, complaining that “the idiots from IT were putting in a new printer which would do every other line backwards, making our documents unreadable!” – without ever waiting for me to explain that all the print came out correctly.

(Turned out that his real objection was to the higher speed. He would queue up lots of print requests, then go take a 10-minute break while the old printer caught up. The new printer kept up so well he couldn’t get away with his extra break or two each hour.)

I’d like to learn to read in this many - are there any programmes that can change texts into this pattern?

When I was in high school, I learned to write this way for two reasons: 1) I was bored, and 2) I had a guy sitting next to me who used to copy off my notes. It drove him wild.

Even today, as a party trick, I can write out whole paragraphs backwards. When people complain they can’t read it, I tell them to turn the paper over and hold it up to a light, or a mirror.

As I’ve gotten older, my normal handwriting has become almost illegible. The funny part is that when I write backwards, the mirrored text is actually far more legible than my normal handwriting.