[comp.os.minix] DMA Discussion

mcd@ccsitn.att.com (09/21/89)

>        I think that I have beat this topic to death.
>        
>        --
>        Doug Ingraham (SysAdmin)
>        Lofty Pursuits (Public Access for Rapid City SD USA)
>        uunet!loft386!dpi
 
Actually the discussion about DMA for PC's has been one of the MOST informative discussion/thread/topics out of all the myriad things I
have seen on the list (outside of reports about some new widget available
for minix).  Thanks a bunch for gainfully employing a few more of my brain
cells.  Discussions like this that do comparisons and present code fragments
are a real aid to understanding.  Instead of an apology for beating a topic
to death, brownie points should be awarded.  Thanx. 

Mike Dickson                att!ccsitn!mcd
                            mcd@ccsitn.att.com
       

root@cca.ucsf.edu (Systems Staff) (09/22/89)

In article <24550@louie.udel.EDU>, mcd@ccsitn.att.com writes:
>  
> Actually the discussion about DMA for PC's has been one of the MOST
> informative discussion/thread/topics out of all the myriad things I
> have seen on the list

Yes, too bad some of it is just plain wrong.

For example, some of the discussion compared a single bus cycle of DMA
to a single bus cycle for CPU transfer where the CPU transfer requires
a bus cycle to fetch and another one to store. Although the the clock
count per cycle may be higher, DMA just requires one bus cycle for a
transfer.

Then there is the issue of interrupt handling time blocking other
interrupts.

Etc. etc.

 Thos Sumner       Internet: thos@cca.ucsf.edu
 (The I.G.)        UUCP: ...ucbvax!ucsfcgl!cca.ucsf!thos
                   BITNET:  thos@ucsfcca

 U.S. Mail:  Thos Sumner, Computer Center, Rm U-76, UCSF
             San Francisco, CA 94143-0704 USA

I hear nothing in life is certain but death and taxes -- and they're
working on death.

#include <disclaimer.std>

gert@targon.UUCP (Gert Kanis) (09/28/89)

In article <24550@louie.udel.EDU> mcd@ccsitn.att.com writes:
>>        I think that I have beat this topic to death.

>Actually the discussion about DMA for PC's has been one of the MOST informative discussion/thread/topics out of all the myriad things I
>have seen on the list
>
>Mike Dickson                att!ccsitn!mcd

May well be,  but *why* does it happen to be in comp.os.minix ??
Do us (and yourselves) a favour and continue in comp.arch (architectures).
There you will reach the "right" audience and get more information out of
it.
AND comp.os.minix will have little better signal/noise ratio :=)

+-----------------------------------------------------------------+
| This was not a flame |  Gert Kanis, SWP                         |
| don't flame back.    |  Nixdorf Computer BV, Postbus 29         |
|----------------------|  4130 EA Vianen, Netherlands.            |
| I do not represent   |  E-mail :     targon!gert@nluug.nl       |
| anyone elses opinion.|  or ..uunet!mcsun!hp4nl!targon!gert      |
+-----------------------------------------------------------------+

root@cca.ucsf.edu (Systems Staff) (09/30/89)

In article <636@targon.UUCP>, gert@targon.UUCP (Gert Kanis) writes:
> >Actually the discussion about DMA for PCs ...
> 
> May well be,  but *why* does it happen to be in comp.os.minix ??
> Do us (and yourselves) a favour and continue in comp.arch (architectures).
> There you will reach the "right" audience and get more information out of
> it.
> AND comp.os.minix will have little better signal/noise ratio :=)

This is just the _right_ place for this discussion. The comp.os.minix
newsgroup is the only forum I have seen on Usenet where there is open
discussion among people actually _writing_ device drivers and similar
code for the PC.

This sort of discussion is very important to them, to anyone who wants
to learn about these issues, and to anyone who wants to make use of the
code they are generating. The latter class includes all Minix users.

Yes, I know about alt.msdos.programmer but the alt groups don't get
general distribution.

 Thos Sumner       Internet: thos@cca.ucsf.edu
 (The I.G.)        UUCP: ...ucbvax!ucsfcgl!cca.ucsf!thos
                   BITNET:  thos@ucsfcca

 U.S. Mail:  Thos Sumner, Computer Center, Rm U-76, UCSF
             San Francisco, CA 94143-0704 USA

I hear nothing in life is certain but death and taxes -- and they're
working on death.

#include <disclaimer.std>