Another very unusual Soviet tube, the ITS1A is an indirect gas discharge display configured for seven-segment number generation. Despite appearances the ITS1A is not a VFD; the device contains seven gas thyratrons, one for each segment, which are painted with green phosphor. When the tube is energized with a high voltage source and a given thyratron is triggered, the neon fill gas will ionize and excite the phosphor in the triggered segment, producing a piercing green glow. As with the ITM2M display shown above, these tubes have complex power supply requirements and must be supplied with separate -300VDC, 100VDC, and 50VDC signals to function properly. Once these needs are met the tube can be controlled with a 5VDC signal, resulting in a neon display that can be directly attached to a microcontroller with no intermediate hardware. The ITS1A is also self-latching, which eliminates the need to multiplex large displays.