[rbanffy]

The line between app platform and OS is a blurry one. The Amiga OS, for instance, has libraries for specific file types that expose standardized entry points. This way, if you install the library for Photoshop files, all graphics programs that adhere to that protocol will be able to read and write Photoshop PSD files. Microsoft had DDE and, later, OLE, for embedding objects from one program into data from another in a standard way all programs were supposed to share. It was a pain.

This blurry line is present in other environments as well. In the Apple Lisa, installing a program resulted in new templates in the Stationery folder. In Smalltalk, installing a program adds its class definitions to the system as independent entities you could use in your own programs.

Not all operating systems are the children of Unix and VMS.

[bitwize]

Smalltalk's components were so tightly interdependent that their integration smoke test was 4+3, because evaluating a simple addition expression exercised like 3/4 of the entire system.

[rbanffy]

I remember once crashing Squeak by doing

`True := False`

Should crash any vintage ST/80 workstation.