Catalog > Semiconductors > Integrated Circuits 8237A-5 P Programmable Memory 4-Channel Programmable Direct Memory Part No: 8237A-5 P 18.98 ZAR inc for 1 Each (Quoting) Add to Cart Specifications, Prices & Availability may change without notice. Images are for illustration purposes only. E&OE Specifications 4 Independent Channels: Each channel can be individually programmed and has a 64K address and word count capability. Transfer Modes: Single Transfer: Releases the bus after every byte. Block Transfer: Moves the entire data block in one go. Demand Transfer: Continues transferring as long as the external device requests it. Cascade: Allows multiple 8237A chips to be "daisy-chained" to increase the number of channels (e.g., how the IBM PC used two 8237s to get 7 channels). Memory-to-Memory Transfer: It can move data from one memory location to another, a feature not found in many other DMA controllers of its era. Auto-Initialization: Allows a channel to automatically re-load its original starting address and word count after a transfer finishes (useful for repetitive tasks like CRT refreshing).