You probably know this, but it's the same stuff -- I would wager a hunk of the original interface builder code written for the NeXT machine runs on your Mac today when you use the interface builder part of xcode (though I haven't looked recently). You probably know this too, but all those classes that begin with the "NS" prefix come from "NeXT Step" -- same stuff, just updated.

It seems likely to me that all these dev tools from 1991 have something to do with why there are > 1M iPhone apps today. That and the enormous market attracting developers...

What was in the Next box CPU wise? You would need Rosetta or something like it to run the old binaries... though it would be awesome if someone implemented this (in fact... bring back rosetta, ffs!)

The original NeXT was Motorola 68030; but performance got decent after they added the 68040 running at either 25Mhz or 33Mhz (which was called the NeXT Mono Turbo if the display was mono or Turbo Color if 4096 colors display).

CPU Motorola 68030 @ 25 MHz, 68882 FPU @ 25 MHz, 56001 digital signal processor (DSP) @ 25 MHz

https://en.m.wikipedia.org/wiki/NeXT_Computer

Interface Builder remained nearly unchanged all the way up until Project Builder turned into Xcode and shortly after IB got blended in. Here's a screenshot from IB under OS X 10.2: https://cl.ly/0J1g1p1m0T3C

I personally liked the two being separate applications. IB is still great today, but it (and Xcode) slowed down noticeably when the two combined.

It was so much easier to fire up interface builder and build something to play around with ideas than the all-in-one Xcode must define a project of today.

I think anytime I have to create a project in any software, it adds a wall of ceremony that just keep adding more layers. It's the difference between QuickTime Pro and iMovie for editing.

I had almost forgotten about the horrendous horizontal pinstripes in early OS X. Looking back it's hard to understand why people drooled over the early OS X UI.

does this have something to do with rendering on CRTs? How they draw horizontal lines?

No, nothing.