From: sandmann AT clio DOT rice DOT edu (Charles Sandmann) Message-Id: <9908310349.AA12479@clio.rice.edu> Subject: Re: FWAIT emulation in emu387.cc To: eliz AT is DOT elta DOT co DOT il (Eli Zaretskii) Date: Mon, 30 Aug 1999 22:49:37 -0600 (CDT) Cc: dj AT delorie DOT com, djgpp-workers AT delorie DOT com, terra AT diku DOT dk In-Reply-To: from "Eli Zaretskii" at Aug 30, 99 09:59:49 am X-Mailer: ELM [version 2.4 PL20] Content-Type: text Reply-To: djgpp-workers AT delorie DOT com X-Mailing-List: djgpp-workers AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk > How come it works on DOS, you ask? Well, it seems that on DOS, FWAIT > never gets into the emulator! > > Charles, is this expected behavior? I don't know ... there are some bugs in "disabling" the FPU with CWSDPMI on a machine with the FPU - it seems some instructions get executed anyway. Maybe this is the issue? In any case, I found you need a real FPU-less machine to test emulation... > Intel manuals say that FWAIT > generates the coprocessor not present exception when the MP and TS > flags in CR0 are set. I guess Windows sets these flags (although > Intel recommends to leave it cleared) while on plain DOS they remain > unset, right? So long ago ... I don't remember. > The Intel manual says the EIP points to FWAIT when it generates the > exception. So it seems like we need to resurrect that line. Does > anyone remember why it was commented out? I think it was commented when I did the initial V2.0 beta port in 1994 ... I could probably find a copy to find out if it was important... I just burned all the ancient disks onto CD :-)