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To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
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Subject: Re: INB question 
In-reply-to: Your message of "Fri, 19 Sep 1997 08:49:37 +0200."
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Date: Fri, 19 Sep 1997 18:08:13 +0930
From: Mike Smith <mike@smith.net.au>
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> 
> > OBTW, see my trailing comment wrt. transfer rates; if ISA read cycles 
> > are deferred by 1.25us, how do I manage 1.3MW/sec from a user-space 
> > process?  (This is with a P166 on an HX board; nothing special.)
> 
> With a true plain ISA card?  The boot code still uses an inb(0x84) for
> a timing loop, and it seems to get the timing well enough with it.

Yes, a "true plain ISA card".  Specifically, a National Instruments 
AT-DIO32-F; the design is probably 5+ years old.

> OTOH, 800000 transfers per second seem to support your figure.  If the
> transfers are 16 bits wide, this would be ~ 80 % of the theoretical
> maximum.

Read it again.  1.3MegaWords.  Specifically, implying that it's making 
1.3 million 16-bit I/O transactions per second, or 2.6MB/sec.

Yes, this is substantially faster than I was expecting.  8)

mike