From owner-freebsd-hardware Sun Apr 14 12:31:13 1996 Return-Path: owner-hardware Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id MAA08919 for hardware-outgoing; Sun, 14 Apr 1996 12:31:13 -0700 (PDT) Received: from tfs.com (tfs.com [140.145.250.1]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id MAA08914 for ; Sun, 14 Apr 1996 12:31:11 -0700 (PDT) Received: from critter.tfs.com by tfs.com (smail3.1.28.1) with SMTP id m0u8XVl-0003xJC; Sun, 14 Apr 96 12:31 PDT Received: from localhost.tfs.com (localhost.tfs.com [127.0.0.1]) by critter.tfs.com (8.6.12/8.6.12) with SMTP id TAA20337; Sun, 14 Apr 1996 19:00:45 GMT X-Authentication-Warning: critter.tfs.com: Host localhost.tfs.com didn't use HELO protocol To: dk+@ua.net cc: freebsd-hardware@FreeBSD.org Subject: Re: building parallel interface gadget - advice wanted In-reply-to: Your message of "Sun, 14 Apr 1996 19:47:41 +0300." <199604141647.TAA08085@clipper.cs.kiev.ua> Date: Sun, 14 Apr 1996 19:00:44 +0000 Message-ID: <20335.829508444@critter.tfs.com> From: Poul-Henning Kamp Sender: owner-hardware@FreeBSD.org X-Loop: FreeBSD.org Precedence: bulk > My only question is: > > from my understanding, for the data byte t obe output into the (real) > printer, it is necessary to assert select, !initialize and strobe > bits of control register and then lower the signal on the strobe pin, > leaving select and !initialize high. Can it be possible that the > same situation unwantedly occurs during system reset (power-on, reset > by switch, software-executed reboot, etc.)? Not only possible, but also very likely. The parallel port is used by man BIOS's as a status port for diagnostics early in the boot sequence. You should protect yourself from this by encapsulating your commands in something very unlikely like "jH#@@'" -- Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team. http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox. whois: [PHK] | phk@ref.tfs.com TRW Financial Systems, Inc. Future will arrive by its own means, progress not so.