Searching for safe, legal PC link to old computer game DND?

The very first computer game I ever played was DND. This is the 1984 DOS-based game by Daniel Lawrence (see link below).

https://www.youtube.com/watch?v=CNTDedbbQLE

I know there were portals made in order to allow the game to be played on a modern PC, just like the games Oregon Trail, Telengard, Zork, and others. People have made comments they're still playing DND, and Daniel Lawrence's old website referred to a portal (the page it named is no longer active, apparently).

I have Windows 8.1. The searches I have tried resulted in very "iffy" sites that I refuse to use for downloads. I'm looking for not only a SAFE site to get the game, but one that is LEGAL. If there is a payment required of that site, I'm okay with that. I really just want to play the game again for nostalgia.