12 KiB
DVX -- DOS Visual eXecutive
A windowed GUI compositor and desktop shell for DOS, built with
DJGPP/DPMI. DVX combines a Motif-style window manager, dirty-rectangle
compositor, cooperative task switcher, and DXE3 dynamic application
loading into a multitasking desktop environment where applications are
.app shared libraries loaded at runtime.
Targets real and emulated 486+ hardware with VESA VBE 2.0+ linear framebuffer. No bank switching -- LFB or fail.
Features
- Motif/GEOS-style beveled window chrome with drag, resize, minimize, maximize, and restore
- Dirty-rectangle compositor -- only changed regions are flushed to video memory, critical for acceptable frame rates on 486/Pentium hardware
- 32 widget types: buttons, text inputs, list boxes, tree views, list views, tab controls, sliders, spinners, progress bars, dropdowns, combo boxes, splitters, scroll panes, ANSI terminal emulator, and more
- Flexbox-style automatic layout engine (VBox/HBox containers with weighted space distribution)
- Dropdown menus with cascading submenus, checkbox and radio items, keyboard accelerators, and context menus
- Modal dialogs: message box (OK/Cancel/Yes/No/Retry) and file open/save with directory navigation and filter dropdown
- 20-color theme system with live preview and INI-based theme files
- Wallpaper support: stretch, tile, or center with bilinear scaling and 16bpp ordered dithering
- Live video mode switching without restart
- Mouse wheel support (CuteMouse Wheel API)
- Screenshots (full screen or per-window) saved as PNG
- Clipboard (copy/cut/paste within DVX)
- Timer widget for periodic callbacks
- Cooperative task switcher for apps that need their own main loop
- DXE3 dynamic application loading with crash recovery (SIGSEGV, SIGFPE, SIGILL caught and isolated per-app)
- INI-based preferences system with typed read/write accessors
- Encrypted serial networking stack (DH key exchange, XTEA-CTR cipher)
- Platform abstraction layer -- DOS/DJGPP production target, Linux/SDL2 development target
Target Hardware
- CPU: 486 baseline, Pentium-optimized paths where significant
- Video: VESA VBE 2.0+ with linear framebuffer
- OS: DOS with DPMI (CWSDPMI or equivalent)
- Supported depths: 8, 15, 16, 24, 32 bpp
- Test platform: 86Box with PCI video cards
Architecture
The shell runs as a single DOS executable (dvx.exe) that loads
applications dynamically via DJGPP's DXE3 shared library system.
+-------------------------------------------------------------------+
| dvx.exe (Task 0) |
| +-------------+ +-----------+ +------------+ |
| | shellMain | | shellApp | | shellExport| |
| | (event loop)| | (lifecycle| | (DXE symbol| |
| | | | + reaper)| | export) | |
| +-------------+ +-----------+ +------------+ |
| | | | |
| +------+-------+ +----+-----+ +----+----+ |
| | libdvx.a | |libtasks.a| | libdxe | |
| | (GUI/widgets)| |(scheduler)| | (DJGPP) | |
| +--------------+ +----------+ +---------+ |
+-------------------------------------------------------------------+
| |
+---------+ +---------+
| app.app | | app.app |
| (Task N)| | (Task M)|
+---------+ +---------+
App Types
Callback-only (hasMainLoop = false): appMain creates windows,
registers callbacks, and returns. The app lives through event callbacks
in the shell's main loop. No dedicated task or stack needed.
Main-loop (hasMainLoop = true): A cooperative task is created for
the app. appMain runs its own loop calling tsYield() to share CPU.
Used for apps that need continuous processing (clocks, terminal
emulators, games).
Crash Recovery
The shell installs signal handlers for SIGSEGV, SIGFPE, and SIGILL. If
an app crashes, the handler longjmps back to the shell's main loop,
the crashed app is force-killed, and the shell continues running.
Diagnostic information (registers, faulting EIP) is logged to dvx.log.
Directory Structure
dvxgui/
dvx/ GUI compositor library (libdvx.a)
platform/ Platform abstraction (DOS/DJGPP, Linux/SDL2)
widgets/ Widget system (32 types, one file per type)
thirdparty/ stb_image.h, stb_image_write.h
tasks/ Cooperative task switcher (libtasks.a)
thirdparty/ stb_ds.h
dvxshell/ Desktop shell (dvx.exe)
apps/ DXE app modules (.app files)
progman/ Program Manager -- app launcher grid
notepad/ Text editor with file I/O
clock/ Digital clock (multi-instance, main-loop)
dvxdemo/ Widget system showcase / demo app
cpanel/ Control Panel -- themes, wallpaper, video, mouse
imgview/ Image Viewer -- BMP/PNG/JPEG/GIF display
rs232/ ISR-driven UART serial driver (librs232.a)
packet/ HDLC framing, CRC-16, Go-Back-N (libpacket.a)
security/ DH key exchange, XTEA-CTR cipher (libsecurity.a)
seclink/ Secure serial link wrapper (libseclink.a)
proxy/ Linux SecLink-to-telnet proxy (secproxy)
termdemo/ Encrypted ANSI terminal demo (termdemo.exe)
themes/ Color theme files (.thm)
wpaper/ Bundled wallpaper images
bin/ Build output (dvx.exe, apps/, config/)
lib/ Build output (static libraries)
releases/ Release archives
Building
Requires the DJGPP cross-compiler (i586-pc-msdosdjgpp-gcc).
# Build everything (dvx lib, tasks lib, shell, all apps)
make
# Build individual components
make -C dvx # builds lib/libdvx.a
make -C tasks # builds lib/libtasks.a
make -C dvxshell # builds bin/dvx.exe
make -C apps # builds bin/apps/*/*.app
# Clean all build artifacts
make clean
Set DJGPP_PREFIX in the component Makefiles if your toolchain is
installed somewhere other than ~/djgpp/djgpp.
Deployment
CD-ROM ISO (86Box)
The primary deployment method is an ISO image mounted as a CD-ROM in 86Box:
./mkcd.sh
This builds everything, then creates an ISO 9660 image with 8.3
filenames at ~/.var/app/net._86box._86Box/data/86Box/dvx.iso. Mount
it in 86Box as a CD-ROM drive and run D:\DVX.EXE (or whatever drive
letter is assigned).
Configuration
DVX reads its configuration from CONFIG\DVX.INI on the target
filesystem. The INI file uses a standard [section] / key = value
format. Settings are applied at startup and can be changed live from the
Control Panel app.
[video]
width = 640
height = 480
bpp = 16
[mouse]
wheel = normal
doubleclick = 500
acceleration = medium
[colors]
desktop = 0,128,128
windowFace = 192,192,192
windowHighlight = 255,255,255
windowShadow = 128,128,128
activeTitleBg = 48,48,48
activeTitleFg = 255,255,255
inactiveTitleBg = 160,160,160
inactiveTitleFg = 64,64,64
contentBg = 192,192,192
contentFg = 0,0,0
menuBg = 192,192,192
menuFg = 0,0,0
menuHighlightBg = 48,48,48
menuHighlightFg = 255,255,255
buttonFace = 192,192,192
scrollbarBg = 192,192,192
scrollbarFg = 128,128,128
scrollbarTrough = 160,160,160
cursorColor = 255,255,255
cursorOutline = 0,0,0
[desktop]
wallpaper = C:\DVX\WPAPER\SWOOP.JPG
mode = stretch
Video Section
width,height-- requested resolution (closest VESA mode is used)bpp-- preferred color depth (8, 15, 16, 24, or 32)
Mouse Section
wheel--normalorreverseddoubleclick-- double-click speed in milliseconds (200--900)acceleration--off,low,medium, orhigh
Colors Section
All 20 system colors as R,G,B triplets (0--255). Key names match the
ColorIdE enum: desktop, windowFace, windowHighlight, windowShadow,
activeTitleBg, activeTitleFg, inactiveTitleBg, inactiveTitleFg,
contentBg, contentFg, menuBg, menuFg, menuHighlightBg,
menuHighlightFg, buttonFace, scrollbarBg, scrollbarFg,
scrollbarTrough, cursorColor, cursorOutline. Missing keys fall back to
compiled-in defaults (GEOS Ensemble palette). Colors can also be loaded from
standalone .thm theme files via the Control Panel.
Desktop Section
wallpaper-- path to wallpaper image (BMP, PNG, JPEG, GIF)mode--stretch,tile, orcenter
Bundled Applications
| App | File | Type | Description |
|---|---|---|---|
| Program Manager | progman.app |
Callback | App launcher grid with icons; Help menu opens the shell's Task Manager (Ctrl+Esc) |
| Notepad | notepad.app |
Callback | Text editor with File/Edit menus, open/save dialogs, clipboard, and undo |
| Clock | clock.app |
Main-loop | Digital clock display; multi-instance capable |
| DVX Demo | dvxdemo.app |
Callback | Widget system showcase demonstrating all 32 widget types |
| Control Panel | cpanel.app |
Callback | System settings: color themes with live preview, wallpaper selection, video mode switching, mouse configuration |
| Image Viewer | imgview.app |
Callback | Displays BMP, PNG, JPEG, and GIF images with file dialog |
Serial / Networking Stack
A layered encrypted serial communications stack for connecting DVX to remote systems (BBS, etc.) through 86Box's emulated UART:
| Layer | Library | Description |
|---|---|---|
| rs232 | librs232.a |
ISR-driven UART driver with FIFO support, automatic UART type detection (8250 through 16750), configurable baud rate |
| packet | libpacket.a |
HDLC framing with byte stuffing, CRC-16 integrity checks, Go-Back-N sliding window for reliable delivery, 255-byte max payload |
| security | libsecurity.a |
1024-bit Diffie-Hellman key exchange (RFC 2409 Group 2), XTEA-CTR stream cipher, XTEA-CTR DRBG random number generator |
| seclink | libseclink.a |
Convenience wrapper: multiplexed channels (0--127), per-packet encryption flag, bulk send helper |
| proxy | secproxy |
Linux-side bridge: 86Box emulated serial port <-> secLink <-> telnet BBS; socket shim replaces rs232 API |
Third-Party Dependencies
All third-party code is vendored as single-header libraries with no external dependencies:
| Library | Location | Purpose |
|---|---|---|
| stb_image.h | dvx/thirdparty/ |
Image loading (BMP, PNG, JPEG, GIF) |
| stb_image_write.h | dvx/thirdparty/ |
Image writing (PNG export for screenshots) |
| stb_ds.h | tasks/thirdparty/ |
Dynamic array and hash map (used by task manager) |
Component Documentation
Each component directory has its own README with detailed API reference:
dvx/README.md-- GUI library architecture and APItasks/README.md-- Task switcher APIdvxshell/README.md-- Shell internals and DXE app contractapps/README.md-- Writing DXE applicationsrs232/README.md-- Serial port driverpacket/README.md-- Packet transport protocolsecurity/README.md-- Cryptographic primitivesseclink/README.md-- Secure serial linkproxy/README.md-- Linux SecLink proxytermdemo/README.md-- Encrypted terminal demo