ADSP-21991 is a mixed signal DSP controller released by Analog Devices. It has a 16-bit fixed-point DSP core with a maximum operating frequency of 160 MHz, and 40K words of RAM, which can be configured as 32K words of 24-bit program RAM and 8K words of 16-bit data RAM. It also has an external memory interface, a dedicated memory DMA controller, a programmable PLL, and a flexible clock generation circuit, which supports full-speed operation from low-speed input clocks. It also has an IEEE JTAG standard 1149.1 test access port, which supports on-chip emulation and system debugging.