Windows, DMA and VDS

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1 total messages Started by Norbert Unterberg Sun, 12 Apr 1992 10:44

#338

Author: Norbert Unterberg
Date: Sun, 12 Apr 1992 10:44

34 lines
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Hi out there on the net,

I am working on a project where I must read data from a pc board using DMA 
transfers. This piece of software is supposed to run under windows 3.x. So my 
question is:

  What is the best way to do DMA transfers under windows?

I have got the "Virtual DMA Specification" (VDS) from Microsoft. But reading 
this leaves two possible methods to me:

1. Ignoring the VDS software interface and programming the DMA controller 
directly using the linear address of the DMA buffer (i.e. as returned by 
GetSelectorBase). The DMA translation service of the virtual machine or the 
VDMAD will to the translations (linear -> physical address conversion, locking 
etc.) for me.

2. Disabling the DMA translation, getting the physical address by using the 
appropriate VDS function calls, and programming the DMA controller woth these 
values.

What is the best way? Did Microsoft ever suppose a "prefered" way of doing DMA 
transfers?

Thanks in advance!

Norbert

---
SoftStream Development       Phone:    ++49-2335-6 17 86
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