Hacker News Reader

Comment by boole1854 | Hacker News Reader

Ok, so this post is a joke of some kind (there was no 1989 version of Blue Prince).

But it raises an interesting question: would it have been possible to implement that upside down floppy disk puzzle in a game?

1. Was it even possible to insert floppy disks upside down? I lived through the floppy disk era in my childhood, but I have to admit I can't remember if the drives would even let you do this.

2. If the answer to #1 is yes, would there be any way of programmatically detecting the floppy-disk-was-inserted-the-wrong-way state?

View on HN

There are in fact two sided floppies! IIRC they behave a lot like the two sides of a cassette tape, the floppy reader only reads from one side at a time.

A fun fact in that regard: the game Karateka (an actual game for the Apple II) had an easter egg, where the team realized that their game entirely fit in the capacity of one side of a floppy, so they put a second copy of the game on the other side, but set up so that it would render upside-down.

I'd not be surprised if the inclusion of that detail in this post was directly inspired by Karateka.

The Apple II had a non-linear layout of video memory, so programmer Jordan Mechner used a layer of indirection where he had an array of pointers to rows of screen memory.

They realized that inverting the screen was as simple as inverting the row-pointer array. Then they managed to convince Broderbund to ship a double-sided floppy with that change in the software.

The Apple II used single-sided floppy disks so it was possible to insert a double sided disk upside-down to story data on the other side.

If the other side contains other data it should be easy to detect the disk was inserted upside down just by reading it.

Yes. Lots of software was double sided. With a small hand punch would could make non-double sided disks double sided (even if manufacturer said no no).

https://www.webcommand.net/wp-content/uploads/2019/07/commod...

That’s true of 5.25” floppies. The newer, higher capacity, 3.5” floppies had both sides accessible without physically flipping, so all drives only supported inserting the disks in one orientation.

But the Apple II mainly used 5.25” floppies. So I’m not correcting you, just adding more context.

5.25 floppies also taste better.

Semi-related; One of the Zelda DS games required you to close the DS (so the top and bottom screen met), which moved a mark from the top to bottom screen. Was infuriating for me, only figured it out after closing the DS in frustration. Not really something you can do with modern portables, but clever in retrospect.

1. No. For an obvious and good reason.

You absolutely could put in disks upside down.

I recall doing this on my BBC micro with 5.25" disks. In fact, some disks were deliberately designed for this, and had a 'notch' (which you would cover with some tape to make read-only) on both the left and right, so you could set the read-only state for each side individually.

The version of Elite that I played had the standard version on one side, and a version for the "BBC Master" (which had an extra 64KiB RAM) which had more colours than the standard version, on the other.

We're talking about 5,25 inch floppies. It was easy to insert those in any way imaginable including several wrong ones ;)

Yep, my memory was bad.

In my defense, so were 5.25" floppies. Literally the worst.

1. (edited) Yes, but you couldn't run it.

1.a. ...unless you altered the shape of the floppy.

https://upload.wikimedia.org/wikipedia/commons/thumb/2/26/5....

Reply on news.ycombinator.com