This is a USB device that emulates a keyboard, allowing the “playback” of predetermined keystroke sequences. A Microchip PIC 18F2550 microcontroller is used, which includes a hardware USB peripheral. The internal EEPROM stores the keypresses you want the PIC to playback. The EEPROM can be programmed over USB via a Windows command line program I wrote. The keystroke sequences can be changed this way. A microswitch on the rear of the enclosure allows the user to switch between programming/stop and play modes.
I originally made this to be used with a popular PC game that outlawed prerecorded macros. The game could detect software macro programs, but had no real way to detect a hardware emulator. The device can be used for anything though. For example, if you wanted to automate the process of formatting a floppy disk, you could create a configuration file that would hit the windows key, arrow key up to Run, type ‘cmd’ and hit enter, wait one second, then type format a:, etc. There’s a limit of 128 keystrokes, due to the size of the internal EEPROM.