DEF SEG

[tim van deelen]

I AM TRYING TO FIGURE OUT HOW TO USE DEF SEG.
HOW DO YOU KNOW WHAT SEGMENT TO USE OR WHAT NUMBER TO USE
WITHOUT CAUSING A PROBLEM. HOW DO YOU KNOW WHAT EACH SEGMENT
IS USED FOR ? ANY HELP WOULD BE GREAT. THANK YOU ALL.

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[Tony Burcham]

Hi tim,
Look under "Memory" in "Ralph Brown's Interrupt List". It has
very detailed information on it. I'm using the one in WinHelp
format.

Tony Burcham


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[Michael Mattias]

DEF SEG is only used to set up conditions used by other functions such as PEEK, POKE, or VARTPR; it is a statement which has no real meaning except in those contexts.

Yes, under MS-DOS certain system tables are always located within certain segments; however, accessing that data requires PEEK or POKE, so again, DEF SEG serves only as a 'setup' for those functions.

MCM

[Ian Cairns]

Michael,
It used to be that if you had data that exceeded the size of your
data segement, then you used DEF SEG to switch among those blocks.
A very necessary function in some circumstances.
regards,

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[email protected]

[Jerry Fielden]

Among other uses, I like to copy Text Screens to a string.

DEF SEG = &HB800  ' is the starting address of a color screen.

a$ = PEEK$(0, 4000)  ' will copy all text and color attributes into a$
CLS                     ' you can clear the screen
                       ' Segment already set
POKE$ 0, a$           ' is a fast way of putting your screen back

DEF SEG                ' back to its default segment

You would want to use DEF SEG if you wanted to BSAVE a screen to a file

DEF SEG = &HB800
BSAVE "TEXT.bsa",0, 4000
CLS                            'Clear the screen
'Segment already set, don't need to reset it
BLOAD "TEXT.bsa             'Put the screen back
DEF SEG    'Reset to Default

If you are BLOADing a screen from a file that has been saved before,
You would want to use DEF SEG = &HB800 on it first.

For Monochrome monitors you would use setting &HB000 instead of &HB800.

Read about BSAVE in your manuel, it should have something about DEF SEG.




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[tim van deelen]

thank you for the help. after reading all the coments about
mr. bush i was sorta afraid to post a topic. it's always
nice to get just help without the strange comments.

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[Jerry Fielden]

There is a few who makes strange and unwanted comments, but don't
let that bother you. When it comes to dishing out help, most here
are pretty free with it. You might as well get your share of it.

You've got to respect the ones who sees their mistakes and apologize
for it.

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[tim van deelen]

that's true if someone says sorry we must forgive and just
remember we have all made mistakes in the past. the biggest
mistake i made was not finding powerbasic sooner!

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