You can also try the TANBUG monitor or BASIC using
Oh... just for the contest temperature... I've heard it from himself, Geoff Phillips is working on a 1 K Microtan Chess program ! 8-)
Now, if you want to get serious with Microtan programming, you surely want to download the Microtan emulator (with sources) on your hard disk: the microtan class is also an application you can run with your favorite Java Run-Time Environment (see Sun's page if you don't have one), thus giving you access to load/save capability (respectively F2 and F3). Just run it like this: jre microtan (or "java microtan" if you use the JDK). See arguments definition in file microtan.java.
Developers: if you prefer to use cross-development tools for
the microtan, here is the format of the Microtan emulator dumps, they consists
in: the ram contents, the graphics bits (512 bits = 64 bytes), and the
processor state (7 bytes for PC, PSW, A, X, Y, S in this order).