A short video describing and demonstrating the Texas Instruments TIL311 device, which is an unusual 'combo' circuit that combines a TTL logic IC and a pseudo dot-matrix LED display.
It takes 4-bit binary data, ranging from binary 0000 to 1111 (decimal 0 - 15, or hexadecimal 0 - F), encodes it in the TTL chip, and then drives the LED dots to form the number 0 - 9 and letters A - F, for a hexadecimal display. LED current is regulated by the IC, so no resistors are needed. However, the package also has two decimal points, one on either side of the displayed digit, and these are not driven by the IC; their cathodes are brought out to pins and they may be driven by external circuitry if needed in an application.