How was the first Windows programmed? Back in 1985, tools didn't really exist that allowed compiling and text input.. After Windows was created, has Microsoft just been building the next version of Windows using the current version of Windows? Sorry it's kind of a random question, but it's one I've been wanting to ask a long time.

With a computer.


See Pascal and ASM. The software for the original Macintosh was written in those two languages. Presumably, Windows 1.01 was written in Pascal/ASM or maybe C... I don't know for sure; I do know there was a C and a Pascal SDK for Windows 1.03.

from the evidence i've seen, it was asm (the person who ported win1.x to the rm nimbus pc-186 said so)

Its written mostly in C of course,while drivers used a lot of assembly.
NT was developed on OS/2 and an emulator while for Windows 1.0 they developed a few DOS tools.
From what I found out windows 1.0 was programmed using a a special version of MS C 3.0 a resource compiler that used a very small buffer and an black white icon editor.
These tools and all you headers you need but not the compiler and startup code were supplied in DR5 and later prereleases here on FTP.
The first other language they supported, was MS Pascal and later Borland adapted their compilers to win16.
I did not try but it could be possible to use the Borland Pascal or C IDE to write homebrew
real-mode software for 2.11 or DR5.
Watcom is open source but would need patching because stack layout is different in real mode on Windows and resource files and bitmaps and fonts are not in the same format.