Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!rochester!pt.cs.cmu.edu!b.gp.cs.cmu.edu!Ralf.Brown@B.GP.CS.CMU.EDU
From: Ralf.Brown@B.GP.CS.CMU.EDU
Newsgroups: comp.binaries.ibm.pc.d
Subject: Re: 256keys:  Interesting to those of you who took it...
Summary: might be able to expand to 128 keys anyway
Message-ID: <231e8201@ralf>
Date: 2 Sep 88 12:12:01 GMT
Sender: netnews@pt.cs.cmu.edu
Lines: 30
In-Reply-To: <4050@ritcsh.UUCP>

In article <4050@ritcsh.UUCP>, sic@ritcsh.UUCP (Eric A. Neulight) writes:
}   IBM's PC BIOS keyboard interrupt routine assumes that the keyboard
}type-ahead buffer resides somewhere within segment 40h (BIOS' data segment).
}
}   It appears that in many '386 machines, and I guess some other types,
}even though BIOS may be compatible and hardcode the buffer within segment 40h,
}DOS loads higher in memory, therefore loading 256keys even higher, past
}the 10200h cut-off.  How do you get around it (aside from burning a patched
}BIOS ROM [don't think it hasn't crossed my mind])?  I do not have access to

It wouldn't be the 386 machines' fault, but rather a recent version of DOS.
DOS has really grown since 3.1, so I'm not surprised that it now uses too much
memory.  You may still be able to expand the buffer to 128 keys, though.

In both DOS 2.10 and 3.10, the area from 60h:0 to 70h:0 is unused!  DOS 1.x
loads beginning at 60h:0, but DOS 2.10 and 3.10 load starting at 70h:0.  As
far as I can tell, all 60h:0 is ever used for in these versions is by the
boot sector, which loads the first directory sector at 50h:0 (thru 70h:0),
and then only looks at the first two entries.

No guarantees, but if you twiddled the BIOS keyboard buffer pointers to move
the buffer to 60h:0, you should be able to get a 128-key buffer.  Disclaimer:
I haven't tried it, and have no need to, as DESQview gives a 128-key buffer
for EACH program anyway.

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