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Article #1022Really weird things with 8250's, PC/XT's, IRQ's and I/O
From: aki
Date: Wed, 19 Aug 1992 08:50
Date: Wed, 19 Aug 1992 08:50
28 lines
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1634 bytes
I have been working on a PC diagnostics program for some time now. Today I became aware of a problem that had never surfaced earlier. It seems that serial port testing code that works perfectly on every computer I've tried it on; suddenly starts malfunctioning on a PC/XT with an 8 MHz V20. The code consists of a _huge_ amount of inp's and outp's with IRQ's blazing at full speed (well... c. 900 times per sec anyway). The funny thing is, that after disabling interrupts for the duration of all I/O functions, I ended up with less problems. Even more elusive is the exact nature of the "bug". I run the same function two times perfectly with _no_ problems; on the third try it bombs. Is this an obvious "see figure 1", or am I tracking something that my time is going to be wasted on? I know there won't be too many PC/XT users with NEC V20's out there rushing to use my program; thus I could label this as a "feature". Anyway, I'd greatly appreciate any input on this phenomena. Aki. -- / Phone: 408-662 9664 Fax: 662 9676 | "Aki" pronounced: Ah-Key. I know \ \ 125 Searidge Ct #D, Aptos, CA 95003 | what I'm doing most of the time. /
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Path: arc1-ca.pugleaf.net!sparky!uunet!charon.amdahl.com!pacbell.com!mips!decwrl!csus.edu!netcom.com!netcomsv!cruzio!aki From: aki@cruzio.santa-cruz.ca.us Newsgroups: comp.os.msdos.programmer Subject: Really weird things with 8250's, PC/XT's, IRQ's and I/O Keywords: What's wrong now? Message-ID: <4071@cruzio.santa-cruz.ca.us> Date: Wed, 19 Aug 92 01:50:25 PDT Sender: news@cruzio.santa-cruz.ca.us Reply-To: aki@cruzio.santa-cruz.ca.us Lines: 28