Date: Tue, 10 Dec 1996 20:04:24 -0800 (PST) From: Jonathan Mini <mini@momentum.nike.efn.org> To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: Robert Eckardt <roberte@mep.ruhr-uni-bochum.de>, joed@telecom.ksu.edu, freebsd-emulation@freebsd.org Subject: Re: bochs (386 emulation) Message-ID: <Pine.BSF.3.91.961210195613.11357E-100000@momentum.nike.efn.org> In-Reply-To: <199612100344.OAA12978@genesis.atrad.adelaide.edu.au>
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On Tue, 10 Dec 1996, Michael Smith wrote: > > > Then I started with `bochs -bootA' > > I had to press return since DOS6.22 waits after the `Starting MS-DOS' message. > > FWIW, this is DOS checking the keyboard controller. I think it sends > a 'reset' command and expects a response of some sort; it's been a while > since I looked at that for doscmd. DOS doesn't reset the keyboard at oll.. or wait for anything, because in that case, DOS wouldn't boot without a keyboar,d and I do it all the time. (and I run DOS 6.22) What you are seeing must be a mis-implementation of the BIOS int 16h Keyboard Services, AH=1 (Set the Z flag to indicate if ab ascii character is available on Read (AH=0)), or AH=2. (Return current shift status in AL register) One of those functinos must be causing a block on the process, since MSDOS 6.22's boot code calls those (and no other keyboard services) to check for the "override" commands. i.e. F5, F7 or alt-F5, Alt-F7. These keys (if you don't already know) causes DOS to skip reading in CONFIG.SYS and AUTOEXEC.BAT (F5) or step trough them. (F7) The Alt versions cause it to do the same thing, but don't read DRVSPACE.BIN off of the hard drive(s) and run it. There isn't any other keyboard access being done by the MSDOS boot code. This access isn't even in the boot sector itself, this is in the "final prep" stage, which is started after IO.SYS and MSDOS.SYS are loaded and initialized. This code is replaced by the permanent section of COMMAND.COM (or whatever shell is listed in the SHELL= directive in CONFIG.SYS) Jonathan Mini (mini@momentum.nike.efn.org) Sent from home machine.
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