Bsave

 BBS: Inland Empire Archive
Date: 03-10-92 (09:45)             Number: 183
From: MATT HART                    Refer#: 140
  To: TIM LAWING                    Recvd: NO  
Subj: Bsave                          Conf: (11) Quik_Bas

* In a message to All, Tim Lawing said:
TL *> I have a screen that I want to save.  I have tried to
TL *> understand this from a couple different manuals, still not
TL *> clear.  The screen is Screen 0.  Someone please explain to
TL *> me the process of reading the screen and placing it into a
TL *> file.  Please explain Def Seg to thanks.

DEF SEG is the statement to tell PEEK/POKE/BSAVE/BLOAD which DOS segment to
operate in.  A PC's memory is split into "segments" of 64K
each.  This has to do with the method in which memory is
accessed, with a segment integer and an offset integer.
Since an integer is max at 64K, each segment is 64K in
size.  The screen segment begins (for color) at memory
location B800:000 which is B800 hex segment and 0000
offset.  So if you were to:
        DEF SEG = &HB800
        POKE 0,65
        DEF SEG
This would put an "A" (CHR$(65)) in the upper left side of the screen.  Many
useful things can be learned from accessing different
memory areas, such as whether keys are pending in the
keyboard buffer without actually accessing them, if ctrl
or alt is pressed, if the num lock is on, what screen mode
is current.  To save a screen to a file, you can use BSAVE:
DEF SEG = &HB800 : BSAVE "MYSCR.BIN",0,4000 : DEF SEG
To reload it:
DEF SEG = &HB800 : BLOAD "MYSCR.BIN",0 : DEF SEG

The ending "DEF SEG" resets the segment to the default, which is important.
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 * Origin: Midnight Micro!  V.32/REL  (918)451-3306 (1:170/600)