Date: Fri, 26 Apr 1996 02:52:49 +1000 From: Bruce Evans <bde@zeta.org.au> To: bde@zeta.org.au, lehey.pad@sni.de Cc: current@freebsd.org Subject: Re: request for a new "feature" as regards DDB Message-ID: <199604251652.CAA32034@godzilla.zeta.org.au>
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>> Polling the keyboard is destructive too. It took me many hours over >> many months to learn how to poll the keyboard on XTs. Early attempts >> used the 8259 to poll for interrupts. This didn't work well because it >> changed the state of the 8259. AT keyboards are much easier. >Do we still need support for XT keyboards? :-) Lowbug polls the >keyboard, and I haven't had any problems with it. FreeBSD never supported them. My debugger does. I won't break it :-). >> And that you can read the counters. The counters for timer0-3 are >> always readable. Only the counters for periods >= 1 second in the RTC >> are readable. >We're really only talking about a 30 second (or whatever) timeout >here. The RTC counters would do just fine for that. Except they will be stopped when you're tracing resettodr() and any other time RTCSB_HALT happens to be set due to a bug. More importantly, they are can't be read without destroying the state of the (write-only) RTC index register. Bruce
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