Where is the screen memory in a CGA 8088?

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4 total messages Started by Bruce Hansen Thu, 08 Mar 1990 20:44

#1517

Author: Bruce Hansen
Date: Thu, 08 Mar 1990 20:44

9 lines
699 bytes

The subject pretty much tells it all.  I want to be able to poke()
a character right into the screen memory so it will show up on the
screen as soon as it is poked.  I read in an Al Stevens book that this
memory starts at b800 for an 8086, but, as that location
does not work for me, I assume it is different for the 8088.

Answers, anyone?

Bruce Hansen

Re: Where is the screen memory in a CGA 8088?

#1527

Author: Joel Spolsky
Date: Sat, 10 Mar 1990 18:48

18 lines
1433 bytes

In article <517@ohs.UUCP> bhan@ohs.UUCP (Bruce Hansen) writes:
>The subject pretty much tells it all.  I want to be able to poke()
>a character right into the screen memory so it will show up on the
>screen as soon as it is poked.  I read in an Al Stevens book that this
>memory starts at b800 for an 8086, but, as that location
>does not work for me, I assume it is different for the 8088.


For all modes except mode 7 (MDA):  B800:0000
For mode 7:			    B000:0000

CPU doesn't matter.

+----------------+----------------------------------------------------------+
|  Joel Spolsky  | bitnet: spolsky@yalecs.bitnet     uucp: ...!yale!spolsky |
|                | internet: spolsky@cs.yale.edu     voicenet: 203-436-1538 |
+----------------+----------------------------------------------------------+
                                                      #include <disclaimer.h>

Re: Where is the screen memory in a CGA 8088?

#1540

Author: Fridrik Skulason
Date: Sun, 11 Mar 1990 16:12

11 lines
951 bytes

In article <18675@cs.yale.edu> spolsky-joel@CS.YALE.EDU (Joel Spolsky) writes:
>For all modes except mode 7 (MDA):  B800:0000
>For mode 7:			    B000:0000
>
Minor correction: Some EGA and VGA cards provide 132x25, 132x43 or 132x50
B/W modes where the screen memory also starts at B000:0000

-- 
Fridrik Skulason   University of Iceland     |     
Technical Editor Virus Bulletin (UK).        |
E-Mail: frisk@rhi.hi.is   Fax: 354-1-28801   |

Re: Where is the screen memory in a CGA 8088?

#1533

Author: Stephen M. Dunn
Date: Sun, 11 Mar 1990 18:32

16 lines
1375 bytes

In article <517@ohs.UUCP> bhan@ohs.UUCP (Bruce Hansen) writes:
$The subject pretty much tells it all.  I want to be able to poke()
$a character right into the screen memory so it will show up on the
$screen as soon as it is poked.  I read in an Al Stevens book that this
$memory starts at b800 for an 8086, but, as that location
$does not work for me, I assume it is different for the 8088.

   Regardless of processor type, CGA memory starts at b800.  Note that
there are multiple display pages at 4K intervals, although it is
exceptionally rare that a program will exit with a different display
page selected than the first one.
-- 
Stephen M. Dunn                               cs4g6ag@maccs.dcss.mcmaster.ca
          <std_disclaimer.h> = "\nI'm only an undergraduate!!!\n";
****************************************************************************
    "So sorry, I never meant to break your heart ... but you broke mine."

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