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Groups > comp.os.msdos.programmer > #3201

Re: Loading DOS high on a XT

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T,

> I thought BIOS sets up RAM addressing. How do you integrate a
> selfbuilt module?

The same way the other "extension cards" (like video, ethernet and others) 
do it for their extension ROMs (and RAM): pick a spot (above the 640K 
border) where no other card claimed/got its and go sit there.

Its also possible that the 128KByte was not available as a contiguous range, 
but instead in smaller blocks that had to be selected ("bank switching". 
like, if I'm not mistaken, EMM did it).

The "self build" might be about having designed the circuitry and soldered 
the chips himself.   The actual access to such memory ranges has been 
build-into the motherboard from the start.

And by the way, in that XP timeframe the addressing is "set up" by the 
processor and other hardware on the motherboard.   The "BIOS" is nothing 
more than a collection of on-board and extension-card ROMs, exposing a set 
of basic APIs and initialisation routines (in short: software).   Nothing in 
there can dictate how the addressing happens (other than to "pretty please" 
the available hardware).

Regards,
Rudy Wieser

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Thread

Loading DOS high on a XT Ruud <Ruud.Baltissen@apg.nl> - 2012-07-15 23:16 -0700
  Re: Loading DOS high on a XT Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-07-16 02:58 -0400
  Re: Loading DOS high on a XT "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-07-16 05:10 -0400
    Re: Loading DOS high on a XT Ruud <Ruud.Baltissen@apg.nl> - 2012-07-17 01:37 -0700
      Re: Loading DOS high on a XT Jim Leonard <mobygamer@gmail.com> - 2012-07-17 14:11 -0700
        Re: Loading DOS high on a XT Ruud <Ruud.Baltissen@apg.nl> - 2012-07-17 22:36 -0700
  Re: Loading DOS high on a XT T. Ment <t.ment@protocol.invalid> - 2019-03-30 04:58 +0000
    Re: Loading DOS high on a XT "R.Wieser" <address@not.available> - 2019-03-30 08:04 +0100
      Re: Loading DOS high on a XT src153 <src153@protocol.invalid> - 2019-03-30 15:17 +0000
        Re: Loading DOS high on a XT "R.Wieser" <address@not.available> - 2019-03-30 19:30 +0100
          Re: Loading DOS high on a XT src153 <src153@protocol.invalid> - 2019-03-30 18:56 +0000
            Re: Loading DOS high on a XT "R.Wieser" <address@not.available> - 2019-03-30 21:18 +0100
              Re: Loading DOS high on a XT src153 <src153@protocol.invalid> - 2019-03-30 21:22 +0000
                Re: Loading DOS high on a XT src153 <src153@protocol.invalid> - 2019-03-30 23:09 +0000
                Re: Loading DOS high on a XT src153 <src153@protocol.invalid> - 2019-03-30 23:34 +0000
                Re: Loading DOS high on a XT "R.Wieser" <address@not.available> - 2019-03-31 10:25 +0200
        Re: Loading DOS high on a XT Rod Pemberton <invalid@lkntrgzxc.com> - 2019-04-02 18:05 -0400

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