chapter 3 - part i.ppt
TRANSCRIPT
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8/10/2019 Chapter 3 - Part I.ppt
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The x86 Microprocessor - Lyla B Das 1
CHAPTER 3
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The x86 Microprocessor - Lyla B Das 2
DOSDOS stands for Disk Operating Systems. It
coud !e an acronym for any OS" !ut it is most
often used as a s#ort#and for $S%DOS&$icrosoft Disk Operating Systems'.
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BIOS and DOS function calls
A set of functions for using I(O de)ices
Can !e used for dispaying data
Can !e used for inputting data from t#ekey!oard
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T#e .E*IT command is a s#ort#and notationfor
$O+ AH ",CHI-T /H
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DOS 0unction Cai' Read t#e key!oard 1it# ec#o
$O+ AH" 2/
I-T /HT#is ca eits 1it# t#e ASCII )aue of t#e key
pressed" !eing a)aia!e in A4 .
T#e key pressed is aso echoed on t#e screen
.
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DOS 0unction Ca 5 Contd.ii' Read 6ey!oard 1it#out ec#o
$O+ AH" 27
I-T /HT#is ca eits 1it# t#e ASCII )aue of t#e key
pressed !eing a)aia!e in A4 .
T#e key pressed is not echoed on t#escreen
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Dispaying a c#aracteriii' 8rite a c#aracter to t#e standard dispay
unit.
0or t#is "t#e ASCII )aue of t#e c#aracter to !edispayed s#oud !e in D4
$O+ D4" 9S:
$O+ AH" 2
I-T /H
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The x86 Microprocessor - Lyla B Das 8
STRI-; DISP4A