Intel 8237 is a direct memory access (DMA) controller, a part of the MCS 85 microprocessor family. It enables data transfer between memory and the I/O with reduced load on the system's main processor by providing the memory with control signals and memory address information during the DMA transfer.
The 8237 is a four-channel device that can be expanded to include any number of DMA channel inputs. The 8237 is capable of DMA transfers at rates of up to 1.6 megabyte per second. Each channel is capable of addressing a full 64k-byte section of memory and can transfer up to 64k bytes with a single programming.[1]
A single 8237 was used as the DMA controller in the original IBM PC and IBM XT. The IBM PC AT added another 8237 in master-slave configuration, increasing the number of DMA channels from four to seven.[2] Later IBM-compatible personal computers may have chip sets that emulate the functions of the 8237 for backward compatibility. The Intel 8237 was actually designed by AMD (called Am9517[3]). It was part of a cross licensing agreement, allowing AMD to manufacture Intel processors, that made the design available for Intel as well. This is why the Intel package has "(C) AMD 1980" printed on it. The 8237, that operate at 3MHz and 5MHz was made by Intel as described in variants while NEC has developed the μPD71037, a version that operates at 10MHz.[4]
- ^ Intel microprocessors by Barry B Brey
- ^ N. MATHIVANAN (2007). PC-BASED INSTRUMENTATION: CONCEPTS AND PRACTICE. PHI Learning Pvt. Ltd. pp. 227–229. ISBN 978-81-203-3076-4.
- ^ "Am9517A Multimode DMA Controller" (PDF). Retrieved 2024-01-04.
- ^ "pPD71037 Direct Memory Access (DMA) Controller" (PDF). Retrieved 2024-01-04.