As long if you don't have the software to run it as floppy, disable the ATNA output by opening jumper J4. The ATNA circuitry immediately pulls DATA low if the ATN line goes active and the computer hasn't yet recognized that. Also a small example for a infrared control is also implemented. When the system comes up and detects an error, the LED is giving a blink code. You get the prompt of the running shell.
Devices are a small key devices, that handles the keyboard interface.
The null device is a neverfilling trashcan. The spooler device can serialize file transfers. As the Gecko has no MMU, all programs share the same memory. So in an 8 kByte system, you still have 4 kByte for your purposes. It is recommended to start zeropage use at 128.