Program Segment Prefix: Difference between revisions

Revision as of 17:19, 28 March 2005

Revision as of 20:40, 20 June 2005

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It has the following strucutre:

Offset Size ContensContents

--------------------------------------------------------------------

00-01 Code CP/M exit (always contain INT 20)

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04 Reserved

05-09 Code Far call to DOS (internal)

0A-0D DWord Terminate address of previosprevious program (old INT 22)

0E-11 DWord Break address of previosprevious program (old INT 23)

12-15 DWord Critical error address of previosprevious program (old INT 24)

16-17 Word Parent psp segment (PSP of caller - usually

command.com - internal)

18-2B Bytes [[Job File Table]](JFT) (internal)

2C-2D Word EnviromentEnvironment segment

2E-31 DWord SS:SP on entry to last INT 21 call (Internal)

32-33 Word Max open files (Internal - see below)

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50-52 Code CP/M function call (always contain INT 21 + RETF)

53-5B Reserved

5C-6B Unopened StandartStandard FCB 1

6C-7F Unopened StandartStandard FCB 2 (overwritten if FCB 1

is opened)

80 Byte Number of characters on command-line (excl. filename