DMAS

DMAs may refer to two widely used concepts in technology and media research: Designated Market Areas in broadcast media and Direct Memory Access in computer systems. Each usage belongs to a different field and has its own terminology and applications.

Designated Market Areas (DMAs) are geographic regions used by Nielsen Media Research to measure local television audiences and to plan advertising. Boundaries reflect where viewers receive the strongest local signals and viewing patterns, not political borders. There are about 210 DMAs in the United States. Markets can cross state or county lines. Ratings and advertising inventory are reported at the DMA level to compare market sizes and guide local campaigns.

Direct Memory Access (DMA) enables peripherals to transfer data to or from system memory without continuous CPU intervention. A DMA controller is programmed with source and destination addresses and a transfer length; it then handles the memory bus transfers, signaling the CPU when complete. Modes include cycle stealing and burst transfers. DMA reduces CPU load and increases throughput, and is common in disk I/O, network interfaces, audio, and graphics devices. Modern systems use bus mastering on PCI/PCIe devices or integrated DMA engines, with IOMMU protection and cache considerations to maintain data integrity.

In summary, DMAs can refer to distinct concepts in different domains; context determines which interpretation applies.