Re: Show me the document RE: Legacy Terminology RE: DMA across PCI

["J. J. Farrell" <jjf@bcs.org.uk>]

> From: Lame Brooks-G14738 <brooks.lame@motorola.com>
> 
> > DMA is Not an ISA only term,
> > A DMA is a chunk of hardware that 
> ..snip..
> 
> DMA is an acronym, not a piece of hardware.  A DMA is a transaction.  A DMA
> _controller_ or _engine_ is a piece of hardware.  I've haven't been in the
> PC industry for more than a decade, so I'm not sure if the term DMA was
> coined earlier than or beside the ISA bus.

I regularly came across and used the term "DMA" in several different
contexts for well over 10 years before I first became polluted by
the PC "architecture". It certainly isn't an ISA term.

> I would bet
> that the authors of the PCI Specification decidely did not use the term
> "DMA," instead using the terms initiator, target, master, and slave
> specifically to avoid confusion with ISA DMA.

Very likely. PCI was defined with PCs very much in mind, and with PCs
as the main target application. The PC has a tendency to grab widely
used industry terms, and corrupt and bend them to fit into its own
little twisted world - consider "windows" for example. PCI mastering
to "main" memory by any device other than a CPU is "DMA" in its proper
sense. When much of the target audience has been mislead into thinking
that "DMA" refers explicitly to some kludge on a PC, an author is wise
to avoid using the term at all since it will probably confuse somebody.