SolarOS 4.16.15 manual · app

Tiny386

Tiny386 is an external foreground app for ESP32-S3 devices with PSRAM, graphics, and native-module support. It emulates a 386 PC with 2 MiB RAM, 256 KiB VGA RAM, PS/2 keyboard, timers, RTC, a floppy drive, and an IDE hard drive. SeaBIOS and the VGA BIOS are embedded in the module. Guest disk images are supplied separately. Networking, mouse, and audio are not supported.

Quick reference

tiny386 /sdcard/tiny386/dos.img
tiny386 /sdcard/tiny386/dos.img --hdd /sdcard/tiny386/harddisk.img
tiny386 --hdd /sdcard/tiny386/bootable-harddisk.img
session create tiny386 display0 /sdcard/tiny386/dos.img
session close ID

Installation and images

Copy solaros_native_tiny386.app.elf to modules/apps/tiny386.elf in the preferred storage volume. The firmware must support the foreground disk-image service methods. The app requires at least 5 MiB free PSRAM and reserves a 16 KiB worker stack; startup can fail if memory is fragmented or other apps retain large allocations.

Use a bootable raw floppy .img of 720 KiB, 1.2 MiB, 1.44 MiB, or 2.88 MiB. An .img extension alone does not distinguish a floppy from a hard-disk image. Use --hdd to attach one raw IDE disk with 512-byte sectors, smaller than 2 GiB. Disk data is accessed directly from storage. Keep an original copy when using a guest that modifies its disks. A bootable hard disk can start without a floppy; with both attached, SeaBIOS tries the floppy first.

Create a formatted 32 MiB hard disk with disk create /sdcard/tiny386/harddisk.img 32. It is ready for files but does not contain a bootable OS. Boot a DOS floppy to install DOS onto the hard drive. For FreeDOS, run these commands from the booted floppy:

FDISK /MBR
SYS C:

FDISK /MBR installs the master boot code while keeping the existing partition and files. SYS C: installs the DOS boot sector and system files. The partition created by disk create is already marked active. Close the emulator, then launch it with only --hdd to boot from the hard disk. See disk images to copy files into it from SolarOS.

Display and controls

The app queries the selected foreground display and allocates a matching frame. Text uses the guest VGA font, character attributes, and cursor. Cell size depends on the number of guest columns and rows: an 80-column screen on a 480-pixel display has six pixels per character. Graphics retain their aspect ratio. Guest RTC starts at 2000-01-01.

Letters, punctuation, Ctrl and Shift combinations, function keys, and navigation keys go to the guest PS/2 keyboard. SolarOS session shortcuts retain their normal function. Ctrl+] or session close ID closes the app.

Sessions and disk saves

Alt+Tab, Alt+Right, Alt+Left, and session fg ID switch sessions. Suspend retains the CPU, guest RAM, VGA state, and exclusive disk claims, pauses guest time, and releases presentation resources. Resume clears held keys and redraws the screen.

Guest writes update and sync the image file before the disk operation returns; storage must be writable. Read, write, sync, or close failures are reported to the launching shell. Close the guest cleanly before removing storage or mounting its image in SolarOS. A suspended guest still owns its disks. Power loss during a write or a guest's incomplete filesystem update can lose data.

See the foreground app contract and module build and BIOS source instructions.