Date: Tue, 22 Jul 1997 03:51:38 +0930 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: luigi@labinfo.iet.unipi.it (Luigi Rizzo) Cc: msmith@atrad.adelaide.edu.au, hasty@rah.star-gate.com, hackers@FreeBSD.ORG, multimedia@FreeBSD.ORG Subject: Re: auto dma? Message-ID: <199707211821.DAA24761@genesis.atrad.adelaide.edu.au> In-Reply-To: <199707211701.TAA21422@labinfo.iet.unipi.it> from Luigi Rizzo at "Jul 21, 97 07:01:59 pm"
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Luigi Rizzo stands accused of saying: > > the intel data sheet for the i82371 (also known as PIIX), a PCI chipset > which implements a number of standard isa devices including timer and > dma controller, is available at the intel site (www.intel.com). > > Although it probably is not exactly the same as the original 8237, it > myght still give some ideas on what to do. It almost certainly uses a "real" 8237 macrocell, so it's likely to behave as near to identically as can be expected. > The main problem with old > peripherals is that they often did not allow a safe reading of 16-bit > registers such as counters, which can be incremented while you read the > two pieces. I don't know if this affected the original 8237, but sure > was a problem with some old PC timer. It was? Unless I'm muchly mistaken, even the 8253 supports the counter latch command. Our gear is full of 8254's; I have bad nightmares every time I have to work on the code that manages them, but for all that they're not _that_ bad. > Finally, if someone is familiar with Linux or NetBSD kernel > (specifically for the isa routines) let me know. Uh, "sorta" (NetBSD). Probably not to the level that you are after though. > Luigi -- ]] Mike Smith, Software Engineer msmith@gsoft.com.au [[ ]] Genesis Software genesis@gsoft.com.au [[ ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ ]] realtime instrument control. (ph) +61-8-8267-3493 [[ ]] Unix hardware collector. "Where are your PEZ?" The Tick [[
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