Re: A82: Checksums and modules

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Re: A82: Checksums and modules

 All the function i have found are listed in 82-ROM.TXT. However the
functions have all been found on the TI85 so any function not yet found can
easily be located. The problem is that the var functions is not placed in
the jump table so you can not be sure you have to add $1A (it might be more
it might be less). So the only thing you can do is to locate the functions
in all the rom version on try to find a way to call them. I want to try to
include these functions in the new shell, but there are a few problems.
First of all the shell will hopefully support some new rom versions which
might make it harder to include the support for them. Secondly i do not know
the addrse in rom version 17 and 18 and unless i can find them i can not
include the functions (does any one have these rom versions ?).

I can not remember the exact header used in ash, but for most programs it is
D9 00 30 (for Ash 3.0). The reason for this is that D9 00 makes sure that
you can not run the program, and 30 is the version. If the program can be
executed using the prgm command the "header" is app. 45 bytes. But all you
need to do is chewck if the first three bytes after the basic program is 00
D9 30. If you need something more precise have a look at some programs, t
should be fairly easy to located the header.

I hav not heard of anyone who has tried to compress anything but BW pictures
on the TI8x calcs, but it might have been done. YOu know ow a SQRXZ world
look, so you should be able to see if the data looks random or not. If it
looks random the method i listed wont work, other wise they might. Try to
encode some worlds using these algorithmes and see how good they are, if
they are good use them otherwise dont.

Dines

-----Original Message-----
From: Thomas J. Hruska <thruska@tir.com>
To: assembly-82@lists.ticalc.org <assembly-82@lists.ticalc.org>
Date: 25. oktober 1997 22:05
Subject: Re: A82: Checksums and modules



>At 11:26 AM 10/22/97 +0200, you wrote:
>>To create,delete,resize variables you need to use the biuld in function
>>(like on the ti85). I have not tested them with Ash, but they might work
>>(try it), they will not work with OS82.
>
>Where are the built in functions in ROM?  Do I need to subtract $1A from
>the address given for ROM 18.0 or not?  Also, what does the 82 header look
>like?
>
>>>BTW, can anyone give me a list of compression algorithms that have been
>>>used for the 82 (and how well they do it)?  My best algorithm can
currently
>>>compress 50 bytes (SQRXZ world) down to 11 bytes (78% compression) using
>>>PCX bitmap style compression.
>>
>>When this was discussed on list-zshell awhile ago, two algorithmes where
>>tried (bith intended to be used with BW pictures).
>
>However, B&smesW pics are not what I want to compress.  A SQRXZ world (not
>pics) is what I want to compress.  Has anybody come up with an algorithm
>that does better compression than the PCX format?  TIA
>
>
>                 Thomas J. Hruska -- thruska@tir.com
>Shining Light Productions -- "Meeting the needs of fellow programmers"
>         http://www.geocities.com/SiliconValley/Heights/8504
>                    http://shinelight.home.ml.org
>