Path: news.mitre.org!blanket.mitre.org!philabs!newsjunkie.ans.net!newsfeeds.ans.net!news-was.dfn.de!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!Supernews60!supernews.com!news.alt.net!usenet From: tony@ercolano.com (Anthony V. Ercolano) Newsgroups: comp.os.ms-windows.programmer.nt.kernel-mode Subject: Re: Parallelport using interrupts Date: Fri, 05 Dec 1997 02:31:07 GMT Organization: Altopia Corp. - Usenet Access - http://www.altopia.com Lines: 57 Message-ID: <348e5fd9.238331312@news.alt.net> References: <661b1l$g5d$1@news.fhg.de> <661iir$emn@news.microsoft.com> Reply-To: tony@ercolano.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Newsreader: Forte Agent 1.5/32.451 I'm not really sure what Frank was looking for, so I let somebody else answer. As for the rest: The performance "degradation" that was experienced with original NT 3.1 beta driver wasn't the primary reason why it was rewritten to be exclusively polling. Some work was done to the interrupt processing to implement throttling that would have made it "better". Note though the interrupt driven driver had GREAT performance as far as benchmarks are concerned. I AM NOT JOKING. The rest of the system may have been slowed down but DO NOT underestimate the need to perform well against brain dead benchmarks. The primary reason the driver was "rewritten" was that it was becoming painfully clear that an interrupt driven parallel driver would cause a *small* (about 1 percent) to simply LOCK up for no good debuggable cause. I lay this down to the fact that the VAST majority of PC's simply had (have?) NEVER been tested by their manufactures with an interrupting parallel port. Note that win 3.1 and win95 didn't have an interrupt driven parallel driver, nor did their implementors think it wise to produce one for much the same reasoning. "Paul Sanders" wrote: >A printer. > >The parallel driver is one of the few drivers that operates in polled mode >when it is capable of operating in interrupting mode. At first glance this >seems counter productive. The reason is that many printers cause interrupts >in a somewhat non-standard fashion. This made it a real pain to write a >good consistent interrupt handler for the parallel driver. As I recall the >straw that broke the camel's back was that every time one of the principal >archtitects of Windows NT tried to print, his mouse became very jerky until >the print job was completed. There were so many interrupts and DPC's being >generated that USER could not move the mouse. Thus, the polled version of >parallel (which is installed by default). > >-Paul > >Tony, did I get this all right??? :-) > >Frank Winkler wrote in message <661b1l$g5d$1@news.fhg.de>... >>Hi folks, >> >>once again a "simple" Problem: I found in the ddk-examples >>comm/parsimp, where interrupts can be "used". Does anybody >>know, where I can find an example, which uses this driver ? >> >>TNX, >>Frank. >> >> >> >> >> >