NOTE: Development on Truecrypt ended in 2014
Alternatives to Treucrypt can be had here
So, I use PortableApps on an external hard drive formatted with TrueCrypt. It's a tasty, secure setup. As with any of my computers, I try to do a re-install maybe 2 – 3 times a year to keep things fresh-n-tasty. Whenever I do this with this external drive, I inevitably go through an initial PortableApps frenzy, installing / creating a bunch of apps on my menu I end up never using. This time, however, there is an exception…
Ladies and gentlemen, I present: the Portable Atari Programming System (with Machine Emulator and Archived References) (md5). Or if you don't like the PAPSMEAR acronym, Portable 2600 Dev will suffice, I guess.
Just extract the .zip to wherever you want and double-click the 2600.exe. This is a simple .NET launcher for SciTE, which has been pared-down to just assembly stuff. Compiling will build via DASM and launch in Stella. Michal Kowalski's 6502 emulator, the Stella Guide, and a pdf'ed 6502 reference I use frequently can be “launched” from within SciTE, as well (you’ll need to open an assembly file, first).