The brains of the quantum dice from DIY Embedded at $25 a throw. The processing power of these USB keys is roughly equivalent to a ZX81 or a BBC micro from the mid 80’s; (likewise the desktop computer of the early 2000’s is now a single-board computer). The largest component is the USB plug. The processor (black square) and 2.4 GHz RF antenna (blue lozenge) are roughly the same size.