Chris, writing at chrisdevblog.com, built GUI apps for Windows 3.11 and OS/2 Warp 3 to control his microcontroller projects on real period hardware. He started with Borland Delphi 1 from 1995, the first and last Delphi that made 16-bit Windows programs. That worked right away, so he switched to Microsoft Visual C++ 1.52 from 1993, where buttons and fields are placed in code instead of dragged onto a form.

Searching the web for Win16 API calls mostly turns up Win32 answers, so he used Charles Petzold’s “Programming Windows 3.1”, a Borland reference, and the Windows 3.1 SDK help built into the compiler. The result talks to his FPGA audio player over the serial port.

Getting the same app running natively on OS/2 meant the Windows Libraries for OS/2, plus patching one byte in the NE executable header to 0x80. The Delphi build failed because the 1991-era WLO libraries don’t have TOOLHELP.DLL, and a replacement based on the ReactOS team’s toolhelp.c didn’t work either.…