Toggtime is a small DOS demo I wrote in October 1995 in Borland Turbo Pascal 7, while I was learning to program. I had just discovered that the 80×25 text-mode screen is really just an array of bytes at memory address $B800 - two bytes per position, one for the character and one for the color attribute - and that Turbo Pascal's absolute keyword lets you map a typed array directly onto it. Instead of the standard Crt approach - GotoXY to move the cursor, Write to output a character - you just assign a byte to any screen position and it appears instantly.
I built it to see that in action. It throws random characters and color attributes at video memory as fast as the CPU allows, and lets you switch modes to isolate what each byte does: colors only, characters only, both at once, or a single random pair frozen across the entire screen.
Thirty years later, in April 2026, I brought it back to life on a modern Mac via DOSBox-X. It still works.
When you launch Toggtime, it starts filling the screen with random characters and color attributes. You can change the mode with single keystrokes:
| Modes | Controls |
|---|---|
| A - Attributes only | P - Pause |
| B - Both attributes and characters (default) | H / Esc - Toggle help screen |
| C - Characters only | Q - Quit |
| U - Unique attributes and characters |
The browser version runs the same DOS program in js-dos, a DOSBox port for the web. Double-click the screen for full screen. After you quit with Q, type TOGGTIME at the DOS prompt to start it again.
Chrome and Edge can also install it as an app, and Safari can add it to the Dock or the Home Screen. It then opens in its own window, but still needs an internet connection.
The ZIP contains the DOS executable, a short readme, and the MIT license. Run TOGGTIME.EXE in DOSBox-X or any DOS-compatible environment.
I build and run Toggtime using DOSBox-X on macOS, with a copy of Borland Turbo Pascal 7.0 downloaded from WinWorld:
- Mount the project directory and the Turbo Pascal installation in DOSBox-X
- Launch
TURBO.EXEand set Options > Directories to point at theUNITS\path - Open
SRC\TOGGTIME.PAS - Press ALT+F9 to compile, Ctrl+F9 to run
What surprised me was how familiar it all felt. Turbo Pascal was one of the first IDEs I ever worked in - along with QBasic and Turbo C++ - when I was learning to program for the first time. And here it is again: the same blue editor, the same compilation dialog, running inside a macOS window with traffic-light buttons. A different frame around a very familiar experience.
Compiling in Turbo Pascal on macOS |
Running on macOS via DOSBox-X |
To build from the command line instead, run python scripts/build.py. It compiles the program in DOSBox Staging without opening the IDE, and checks that the result is byte-identical to the TOGGTIME.EXE in the v1.0.0 release. Set DOSBOX to the DOSBox Staging executable and DOS_C_DIR to the folder that DOSBox mounts as C:, with Turbo Pascal installed in it. The script looks for the compiler at C:\BP\BIN\TPC.EXE; set TPC if yours is elsewhere, for example C:\TP\BIN\TPC.EXE. With --web, it also rebuilds the browser version in web/, and with --package, it writes the release ZIP to dist/.
SRC/
TOGGTIME.PAS main program
UNITS/
STDCHAR.PAS character types and digit/hex constants
CURSOR.PAS BIOS INT 10h cursor + keyboard typematic rate
CRTKEYB.PAS keyboard input with extended-key handling
CRTX.PAS Crt extensions: attributes, windows, frames, sound
VIAT.PAS direct VRAM arrays mapped via the absolute keyword
web/
index.html browser version, running the DOS program in js-dos
toggtime.jsdos js-dos bundle with TOGGTIME.EXE, written by build.py
manifest.webmanifest web app manifest, for installing it as an app
icons/ favicon and app icons
scripts/
build.py build, browser bundle and release ZIP
The five units are small and reusable on their own. They may eventually move into a shared Hello World Writer Pascal library.
Toggtime is licensed under the MIT License.
Made with ❤️ in Oradea, Romania https://www.thehelloworldwriter.com