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Path: utzoo!watmath!clyde!bonnie!akgua!sdcsvax!sdcrdcf!psivax!al
From: al@psivax.UUCP (Al Schwartz)
Newsgroups: net.micro.pc
Subject: Re: Dos Startup modification
Message-ID: <319@psivax.UUCP>
Date: Sun, 10-Feb-85 21:26:43 EST
Article-I.D.: psivax.319
Posted: Sun Feb 10 21:26:43 1985
Date-Received: Wed, 13-Feb-85 02:32:21 EST
References: <307@psivax.UUCP> <431@ahuta.UUCP>
Reply-To: al@psivax.UUCP (Al Schwartz)
Organization: Pacesetter Systems Inc., Sylmar, CA
Lines: 31
Summary: 


In article <431@ahuta.UUCP> dmt@ahuta.UUCP (d.tutelman) writes:
>As has already been pointed out, doing away with the startup test involves
>burning new ROMs.  I disagree with the comment about expense (unless you
>buy an EPROM burner for this one-shot job), but it may be illegal.
>In order to do it, you would need to copy the IBM BIOS ROM onto a
>writeable medium (say, a floppy), edit it, and use the edited version
>as input to an EPROM programmer.  IBM has been sticky about people

Let me know if there are EPROMS available to do this.  I think that the ROMs
that IBM uses have a strange pinout that CANNOT be emulated by standard
EPROMS (27xx series).  I guess one could build some adaptor boards but I
would not consider this to be an elegant solution to the problem.

I have heard that the BIOS ROM determines that the machine has been powered-
up once already by examining two memory locations and checking them against
the pattern 0x12 , 0x34.  I forgot which locations have this (see the BIOS
listing in the Tech. Ref. Manual for more details).  If these locations contain
the pattern then the BIOS skips the memory test.  One could construct a 
circuit that decodes those memory locations to "fool" the BIOS into thinking
that it tested the memory already.  There still has to be software to write
every memory location that you plan to use in order to set the parity bit
at every memory location.  This has to be done with the parity error interrupt
ignored.  I am still not sure if this will work though.  Has anyone out there
tried to do this?
-- 
Yow! Am I having fun yet?             Al Schwartz
                                      Pacesetter Systems Inc., Sylmar, CA 
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