GentleOS/16 hobby OS for vintage 16-bit PCs

GentleOS/16 is a hobby operating system designed for vintage 16-bit personal computers. It requires only an 8086 CPU and a CGA display capable of 320x200x4 resolution. The system is built for tinkering with old hardware using plain C programming language. It has no practical applications, no web browser, and no support for third-party applications. GentleOS/16 is essentially a simplified version of GentleOS/32, a more advanced OS for 32-bit devices that shares most of its design principles.

The project can be accessed through an online PC emulator by visiting a specific webpage. Alternatively, users can download a bootable disk image to run it on a floppy disk, HDD, or USB flash drive. There are two floppy-sized images available: one for a 1.44M drive and another for a 720K drive. The lowest tested hardware configuration is an NEC V20 CPU with 512KB of RAM. For the highest end, the system must still support traditional BIOS/legacy boot, ruling out pure-UEFI systems.

To run GentleOS/16, developers need to recompile the source code with DEBUG_TO_UART enabled in config.h. They can then use Serial USB Terminal on Android, connected via a cheap RS232 to USB-C adapter with PL-2303 chipset and a mini null-modem F-F adapter. The configuration settings include a baud rate of 9600, 8 data bits, no parity, and 1 stop bit.

The author has replaced traditional 720K floppy drives with Gotek emulators for easier development, particularly due to the limitations of modern USB floppy drives. The images were captured using an iPhone 16 and lit using a softbox. Minimal adjustments were made in GIMP for trimming, white balance, exposure, and contrast.

This project is a personal hobby, and the author does not accept pull requests due to the volume of work at their primary job. However, if anyone makes something interesting with GentleOS/16, they are encouraged to share it via email, specifying whether the changes should be included in their branch or on the project's website. The software is licensed under the GNU General Public License, version 2, copyright © 2026 luke8086.