When experimenting with digital and microcontroller-based circuits it is often more convenient to display a value as a number and not as a bit pattern on a row of LEDs. This circuit is designed for exactly that purpose. Thanks to its low current consumption (a little under 10 mA) and its compact construction it can be plugged directly into a header on a microcontroller board, taking its supply from that board. An EPROM, which stores all the required values for display, is used as the decoder. The 256 kbit EPROM is considerably larger than strictly necessary for this job — 1 kbit would be enough — but the type shown is much easier to obtain.