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From: Robert Swindells <rjs@fdy2.co.uk>
Newsgroups: comp.arch
Subject: Re: Architectural implications of locate mode I/O and channels
Date: Wed, 3 Jul 2024 13:09:28 -0000 (UTC)
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On Wed, 03 Jul 2024 05:52:07 GMT, Anton Ertl wrote:

> Interestingly, this is one development that has not been repeated in
> microprocessors AFAIK.  If they did not want to spend hardware on a
> separate DMA device, they just let the software use polling of the I/O
> device.  For the 8086 and 68000, I guess that patents may have
> discouraged adopting this idea; when the patents ran out, they had
> established an ecosystem with separate DMA devices.  And of course for
> the early RISCs there was no way to do that in microcode.

There was the 8089 coprocessor for the 8086, it was used in the Apricot 
PC.

<https://en.wikipedia.org/wiki/Intel_8089>