Alan Kay: It was kind of like what we have today, but better. It was a completely integrated system that was not made up of applications, but "objects'' that yo

Alan Kay: It was kind of like what we have today, but better. It was a completely integrated system that was not made up of applications, but "objects'' that you could mix and match anywhere. You've got a work area and you can bring every object in the system and you just start: You've got every tool, you've got every object, and you can make new objects. It was programmable by end user, and it had the famous GUI. Larry Tesler: It was the first one that was graphically based–overlapped windows, a mouse, stuff like that. Adele Goldberg: It was very much a GUI demo. Dan Ingalls: I was scrolling up some text and Steve said, "I really like this display." Alan Kay: At that time, when text scrolled, it did so discreetly: So jump, jump, jump–like that. Dan Ingalls: And Jobs said, "Would it be possible to scroll that up smoothly?" Alan Kay: "Can you do it continuously?" Steve liked to pull people's chains. Dan Ingalls: Because it did look a little bit jerky, you know? Alan Kay: So Dan or maybe Larry just opened up a Smalltalk window and– Bruce Horn: –changed a few lines of code in Smalltalk, and in the blink of an eye it could do a smooth scroll. Alan Kay: And so it was like, "Bingo!" And so Steve was impressed but he didn't know enough to be _really_ impressed. The other Apple people just shit in their pants when they saw this. It was just the best, best thing I've seen. Dan Ingalls: I think that sort of blew Steve's mind. Certainly, just about anybody who worked on development systems responded really well to that particular demonstration. It really showed how the Smalltalk system could be changed on the fly and be extremely malleable in terms of stuff you could try out in the user interface. Alan Kay: On Smalltalk you could change any part of the system in a quarter of a second. These days it's called live coding, but most of the stuff today–and virtually everything back then–used compiled code, so your programming and editing and stuff like that was a completely separate thing. You had to stop the system and rebuild. Dan Ingalls: So you had a regular sort of programming environment sitting there in front of you with windows and menus and the ability to look at code and stuff. But the neat thing about it was that if you edited the code, it would actually change the code that you were running at that very moment. The object-oriented architecture made it really, really quick to make changes. Bruce Horn: Even today if you wanted to change something at the level of the operating system in MacOS or Windows, it's simply impossible unless they have decided to give you that option to smooth-scroll or not. It's simply impossible to get to the source code to do that unless you're an employee–and even then it would probably take six months to get that feature in. Whereas within Smalltalk, you pop up the menus, accept the change, and it's working right now. You can't even do that today. (from Valley of Genius: The Uncensored History of Silicon Valley)