Microsoft got its start with a BASIC Interpreter and a simple loader called MS DOS, adopted by IBM for the IBM PC as PC-DOS.
Inspired by Graphical User Interface (GUI) work at Xerox PARC, Microsoft wrote a GUI shell for the PC called Windows. The first few versions of Windows were rudimentary toys.
This AT&T 6300 XT class PC is runs MS Windows 1.0 and MS DOS 2.11. The Windows screen is split with MS Write (similar to WordPad) at the top and File Explorer at the bottom.
The CGA screen is capable of displaying 16 colors at 320x200, but here is running in black and white to allow 640x400. The hard disk (top right with red squares) holds 20 MB, the 5 1/4” floppy disk (bottom right) holds 360KB. The system has 640 KB of RAM, the maximum supported.