Other peripherals in the analog area include two programmable excitation current sources and an internal reference. It is also possible to connect an external reference source – popular in ratiometric measurement applications like H-Bridge based designs such as pressure sensors and weigh scales for example. A single 12-bit DAC is also included in the analog portion of the device. The rest of the diagram shows the 8052 core, the RAM and FLASH Memory, communication interfaces (SPI, UART, I2C), timers, and a debug interface. The full list Sigma-Delta based devices is listed in the right hand column of the slide.