Product Details
4-Channel Programmable Direct Memory
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).
Additional Information
| Device | Programmable Memory |