[Coco] WHAT MANNER OF UNHOLY WIZARDRY IS THIS?

[Arthur Flexser]

Having the execution address of end-packed ML code be a few bytes before
the address pointed to by the end-of-program pointer is pretty standard,
BTW.  It allows the Basic program with the end-packed code to be edited,
changing its length, and to still work, assuming the ML is written as
position-independent.  The exec address will still be correct after program
editing because the end-of-program address and the execution address will
move in tandem.  (Step one in setting up such a program is to protect the
ML, and ensure it gets loaded in when the Basic program is loaded, by
poking in a new end-of-program address that points just beyond the end of
the ML that follows the Basic lines.)

Art


On Sun, Apr 20, 2014 at 9:18 PM, Juan Castro <jccyc1965 at gmail.com> wrote:

> I didn't express myself quite right, there's BASIC instructions in
> there that execute it. I said "don't run it" so people could take a
> look at it.
>
> On Sun, Apr 20, 2014 at 9:48 PM, Arthur Flexser <flexser at fiu.edu> wrote:
> > The question is how does that end-packed binary get executed simply by
> > listing the program and not running it?  Or did I misunderstand your
> > description, Juan?
> >
> > Art
> >
> >
> > On Sun, Apr 20, 2014 at 8:38 PM, Juan Castro <jccyc1965 at gmail.com>
> wrote:
> >
> >> Yeah, and now I get it: the BASIC program has a binary part appended
> >> after it, and it gets loaded along.
> >>
> >> On Sun, Apr 20, 2014 at 9:07 PM, Bill Pierce <ooogalapasooo at aol.com>
> >> wrote:
> >> >
> >> > Juan
> >> > Niether can RSDOS and never has as far as I know... the correct syntax
> >> is:
> >> > LOAD"FILENAME/EXT:n"
> >> >
> >> >
> >> >
> >> > Bill Pierce
> >> > "Today is a good day... I woke up" - Ritchie Havens
> >> >
> >> >
> >> > My Music from the Tandy/Radio Shack Color Computer 2 & 3
> >> > https://sites.google.com/site/dabarnstudio/
> >> > Co-Webmaster of The TRS-80 Color Computer Archive
> >> > http://www.colorcomputerarchive.com/
> >> > Co-Contributor, Co-Editor for CocoPedia
> >> > http://www.cocopedia.com/wiki/index.php/Main_Page
> >> > E-Mail: ooogalapasooo at aol.com
> >> >
> >> >
> >> >
> >> >
> >> > -----Original Message-----
> >> > From: Juan Castro <jccyc1965 at gmail.com>
> >> > To: CoCo List <coco at maltedmedia.com>
> >> > Sent: Sun, Apr 20, 2014 7:39 pm
> >> > Subject: [Coco] WHAT MANNER OF UNHOLY WIZARDRY IS THIS?
> >> >
> >> >
> >> > Get the DSK image "ADV2" in this page.
> >> > http://sites.mpc.com.br/ric/cp400/eadv.htm
> >> > Now load the BASIC program called "#" and list it, don't run.
> >> > It gets the address of the end of the BASIC program, subracts 6 and
> >> > UMPS TO IT! And an INTERACTIVE DISK MENU POPS OUT OF NOWHERE!
> >> > What is going on here?
> >> > (Unrelatedly, it seems HDB-DOS can't LOAD or LOADM files with
> >> > n:FILENAME.EXT" syntax. It gives me a ?FN ERROR.)
> >> > Juan
> >> > --
> >> > oco mailing list
> >> > oco at maltedmedia.com
> >> > ttp://five.pairlist.net/mailman/listinfo/coco
> >> >
> >> >
> >> > --
> >> > Coco mailing list
> >> > Coco at maltedmedia.com
> >> > http://five.pairlist.net/mailman/listinfo/coco
> >>
> >> --
> >> Coco mailing list
> >> Coco at maltedmedia.com
> >> http://five.pairlist.net/mailman/listinfo/coco
> >>
> >
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > http://five.pairlist.net/mailman/listinfo/coco
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>