Date: Wed, 23 Feb 2000 05:24:52 +0600 (LKT) From: Kalum Somaratna aka Grendel X-Sender: root AT darkstar DOT grendel DOT net To: djgpp AT delorie DOT com Subject: Re: real mode & protected mode (fwd) Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Reply-To: djgpp AT delorie DOT com On Tue, 22 Feb 2000, Damian Yerrick wrote: > On Tue, 22 Feb 2000 20:47:40 +0600 (LKT), Kalum Somaratna aka Grendel > wrote: > > >What I wanted to comment about was that the loadall insn is a very > >powerful insn and that 32 bit real mode are posiible if loadall is used. > >If needed I can provide the details on how to do this but it is a bit > >lengthy and complex... > > There's another way: go protected, set all segments'limits to 4 GB, go > real. This works on some x86 chips. The original problem was that there was no acceptably fast way of switching back into real mode in the 286. Thats why all the programmers started using loadall. > > >> The 286 and 386 have LMSW that can switch to real or protected mode. The > >> switch took place by setting some flags in the CMOS and some > >> manipulations which was d amn slow. > > ^^^^^^ BTW I had to put a space between the > >highlighted words since the DJ's email gateway rejected the reply saying > >"offensive language not allowed". Thats the second time this hapenned to > >me and through no fault of my own too. Sorry for mentioning this but this > >mail filter is really annoying. > > You can: > 1. say d4mn, $#!+, @$$, etc. > 2. use net: http://www.deja.com/ then comp.os.msdos.djgpp > Followups will be threaded properly if you use net news. Thanks, I am going to use a NNTP server since this is IMHO unwanted discrimination against us guys who use the mailing list. See how many people use the word D4mn, I can't belive that it is tagged as offensive language, I don't want to get into personal attacks but how many people on this list in this modern age would get a heart attack when thay see the word d4amn? things like fsck I can understand but d4amn??. > > > >Actually the BIOS of 386 and above were designed to emulate the 286 > >loadall since the large number of programs that used it. AFAIK RAMDRIVE, > >OS/2 all use/d loadall. > > Did they fail on 486 and up? No they didn't. This is because due to the large amount of programs that use the 286 loadall insn all 386 and 486 and above BIOSes must emulate the insn. On the >386 the 286 loadall generates and invalid opcode exception which is trapped by the BIOS which then does is best to emulate the functionality of the LOADALL insn but as you can see LOADALL is so powerful and so many things can be done with it that _perfect_ emulation is impossible without using loadall itself. One solution was to use the 386 loadall to emulate the 286 loadall but this had it's risks since intel removed the 386 loadall from the 486 and higher. > >Hi, I'm a signature virus. plz set me as your signature and help me spread > >:) > > My virus is sneakier. Yes but too bad it doesn't work for linux ;-) Anyway your virus doesn't seem to be working Damien, I suppose we will get a new "victim" very soon.. Come on my fellow djgpp'ers please set this virus as your sig and help to defeat that infamous Yerrickaffee scan.... Grendel Hi, I'm a signature virus. plz set me as your signature and help me spread :)