Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!ucbvax!pro-angmar.UUCP!m.tiernan
From: m.tiernan@pro-angmar.UUCP (Michael Tiernan)
Newsgroups: comp.sys.apple2
Subject: Re: pipes (implementation thereof)
Message-ID: <3592.apple.net@pro-angmar>
Date: 24 Mar 90 16:27:34 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 21

In-Reply-To: message from alphalpha!toddpw@tybalt.caltech.edu

> DMA does not require interrupts ......

Literally no, but yes it does require an interrupt of sorts.  The DMA request
is handled (inside the CPU) in the same frame of mind as an interrupt is, when
the CPU sees it, it finishes what it's doing (6502's wait till the end of a
read or a write and 65c02's go in the middle of a write) and relenquishes the
data, address, and control buss to the requester and waits for the DMA line to
return to continue processing.


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