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From: markh@csd4.csd.uwm.edu (Mark William Hopkins)
Newsgroups: comp.sys.ibm.pc.programmer,comp.os.msdos.programmer
Subject: Re: DMA Hardware I/O Port Command DOC Needed
Message-ID: <10590@uwm.edu>
Date: 29 Mar 91 01:06:44 GMT
References: <40302@cup.portal.com>
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In article <40302@cup.portal.com> cliffhanger@cup.portal.com (Cliff C Heyer) writes:
>Needed: DMA Hardware I/O Port Command Documentation.

You had to ask... :)

>I need documentation about how to use the DMA controller. I have a list 
>of the ports from the Phoenix BIOS book, but it has no info on the commands.
>
>This documentation should have the ports and the commands to put in the
>ports to make it work, as well as the interrupts used by the DMA chip
>to communicate DMA completion.

This documentation can be found in the book called: IBM Microcomputers
A Programmer's Handbook, written by Julio Sanchez, and Maria Canton.

It describes all the desired things your want for DMA hardware for the
PC, XT, AT, and PS/2 microchannel systems.

The DMA controller is an Intel 8237 or compatible, so reading the Intel
source on the chip will help too.  But it obviously won't tell you hardware-
determined DMA assignments in the various IBM's (such that DMA channel 0 is
used for memory refresh in the XT and PC).