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From: micro@imada.ou.dk (Klaus Pedersen)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: How to use the VDI from the Autofolder
Message-ID: <1991May27.001208.27105@imada.ou.dk>
Date: 27 May 91 00:12:08 GMT
References: <1991May24.184249.21414@imada.ou.dk> <1991May25.152208.2925@actrix.gen.nz>
Sender: news@imada.ou.dk (USENET News System)
Organization: Dept. of Math. & Computer Science, Odense University, Denmark
Lines: 68

Hi, 
Roger send this code, but please don't use it, because:
   o assumes that the ROM starts at $FC0000 (WRONG - might be $E00000 or
     something else.)
   o Don't use the XBRA protocol...
   o Don't use the longframe system var...

Also it say that the Trap2 vector gets taken all the time, I have not 
experinced that (but I am using tos1.4).
The code in the followup to Claus Brod question don't have these problems, 
please try to put the program from the post in the auto-folder, and let me 
know of problems.
And if you use the XBRA protocol you can unlink youself from any vector
chain (if all programs follow the protocol - and most do).
If you use the XBRA protocol you can see if you have been installed.
Please this is no flame, but a WARNING, don't use this code.

Roger.Sheppard@actrix.gen.nz (Roger Sheppard) writes:

>uniquely difficult because the operating system keeps replacing its own
>address in the vector!  TOS seems to reset $88 (trap #2) every time
>you runa .TOS or .TTP program, or show a file from the desktop.
> (And maybe at other times too...)

I have never seen that problem, ones you have it installed, it stays there
just as Allan have tried to say here!!! (Overscan runs - don't it?)
The only problem is when to take the trap2 vector from the AUTO folder.

...
> *  Trap #13 wedge routine

WHAT NO XBRA HEADER, PLEASE REMEMBER!!!

> my_t13:
>        btst    #5,(sp)         ; Super or user mode?
>        beq.s   t13_ex          ; If user mode, let's forget the whole thing
>        cmp.l   #$050101,6(sp)  ; Setexec call for critical error vector?

Say that it is not obvious, it is the same thing my program checks for!!
That is real funny.
This subroutine Don't use XBRA, Don't check  'longframe' don't run in user
mode... Please ()

...
> first_time:
>        tst.l   10(sp)          ; Reading the vector?
>        bmi.s   t13_ex          ; Yes, let the system take care of it
>        cmp.l   #$FC0000,10(sp) ; Is this address below the ROMs?

AUCH, WHAT IS THIS ^^^^^^, DON'T USE ANY THING LIKE THIS...  
THERE IS NO NEW ATARI COMPUTERS THAT RUNS THIS !!!! 



>Anyway, one really important point to remember when you
>steal _any_ of the ST's trap vectors -- once you steal it,
>NEVER reset it to what it was when you grabbed it.
> To disable yourself, use a flag and jump past your code, or some other
>method...if you actually replace the vector itself, you'll be cutting
>out any other programs that have installed themselves in the chain.

This is not true, If you use the XBRA protocol you can unlink yourself (or
any other :-) at any time!!!!


Sorry for disturbing you,

Klaus, micro@imada.ou.dk