YMF724B、YMF724C、YMF724E 的差異

B版:DDMA(Distributed DMA)無法正常運作。

C版:已解決 DDMA 問題,但在 Intel BX 晶片組的主機板上 DDMA 仍無法正常運作。

E版:解決 Intel BX 晶片組的主機板上 DDMA 問題。

什麼是 DDMA?

DDMA is an alternative legacy DMA solution.This techniquee effectively "distributes" the 8237 DMA controller into physically separate PCI resident components on a per DMA basis.

A "Master DMA agent" central resource is located somewhere in the system which orchestrates the legacy I/O traffic to and from the distributed DMA elements of the system.The DMA master intercepts all 8237 I/O register references and redirects,via a software configured lookup,for control/status registers,combined data for all of its DMA channels within single I/O registers,the DMA master typically scatters and gathers several bus transactions to complete a single legacy I/O register read or write.