GENERAL DESCRIPTION
The Am9517 A Multimode Direct Memory Access (DMA) Controller is a peripheral interface circuit for microprocessor systems. It is designed to improve system performance by allowing external devices to directly transfer information to or from the system memory. Memory-to-memory transfer capability is also provided. The Am9517A offers a wide variety of programmable control features to enhance data throughput and system optimization and to allow dynamic reconfiguration under program control.

DISTINCTIVE CHARACTERISTICS
• Four independent DMA channels, each with separate registers for Mode Control,
   Current Address, Base Address, Current Word Count and Base Word Count.
• Transfer modes: Block, Demand, Single Word, Cascade
• Independent autoinitialization of all channels
• Memory-to-memory transfers
• Memory block initialization
• Address increment or decrement
• Master system disable
• Enable/disable control of individual DMA requests
• Directly expandable to any number of channels
• End of Process input for terminating transfers
• Software DMA requests
• Independent polarity control for DR EQ and DACK signals
• Compressed timing option speeds transfers - up to 2M
   words/second
• +5 volt power supply
• Advanced N-channel silicon gate MOS technology
• 40 pin Hermetic DIP package
• 9517A-5 5MHz version for higher speed CPU compatibility