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Product Attributes

Introduction

The Am2940, a 28-pin member of AMD's AM2900 family of Low-Power Schottky bipolar LSI chips, is a high-speed, cascadable, eight-bit wide Direct Memory Access Address Generator slice. Any number of AM2940's can be cascaded to form larger addresses. The primary function of the device is to generate sequential memory addresses for use in the sequential transfer of data to or from a memory. It also maintains a data word count and generates a DONE signal when a programmable terminal count has been reached. The device is designed for use in peripheral controllers with DMA capability or in any other system which transfers data to or from sequential locations of a memory. The Am2940 can be programmed to increment or decrement the memory address in any of four control modes, and executes eight different instructions. The initial address and word count are saved internally by the Am2940 so that they can be restored later in order to repeat the data transfer operation.

Features

• DMA Address Generation: Generates memory address, word count and DONE signal for DMA transfer operation.
• Expandable Eight-bit Slice: Any number of Am2940's can be cascaded to form larger memory addresses - three devices address 16 megawords.
• Repeat Data Transfer Capability: Initial memory address and word count are saved so that the data transfer can be repeated.
• Programmable Control Modes: Provides four types of DMA transfer control plus memory address increment/decrement.
• High Speed, Bipolar LSI: Advanced Low-Power Schottky TTL technology provides typical CLOCK to DONE propagation delay of 50ns and 24mA output current sink capability.
• Microprogrammable: Executes 8 different instructions.