[A83] Re: SDCC Port

To: <assembly-83@lists.ticalc.org>
Subject: [A83] Re: SDCC Port
From: "Henk Poley" <hpoley@dds.nl>
Date: Fri, 7 Feb 2003 22:43:02 +0100
Reply-To: assembly-83@lists.ticalc.org
> Van: Aaron St.John <aaronstj@hotmail.com>
> 
>> Thought about all the different shells? They need different startup
>> code. Heck there isn't even a standard one that you could use that would
>> work in every Ti8x calc. The calcs have minor differences (other than
>> ROM adresses, which can be "fixed" by using the linker) but they are
>> there.
> 
> Yes, I had given that some consideration, and had a number of different 
> thoughts.  One is that, as I only own a TI-83, I'm really only interested
> in making it work for the TI-83.  I suppose other other authors could
> work off my project to create simliar developement kits for other TI
> calculators, but that's their decision, not mine.

Good point, Ti83+ users are bugging be to fix the Ti83+ port of the z88dk.
I don't have one...

> Second is that there is indeed a problem with the multiple shells.
> There are three solutions that I have conbsidered:
> 
> 1) Create the library in such a way that the author can specify which
> shell he wants the program to run on

:-)

Improves portability, other programmers could easely add support for other
Ti-calcs (they have much in common).

> 2) Pick one shell to keep copmatibility with and run with it.  It would
> seem reasonable to pick ION, and it's pretty much become the TI-83
> standard, as far as I can tell, and all new TI-83 shells are ION
> compatible.

<holy-war type="Ti83 shell">
Yes :-(
</holy-war>

> 3) Create a new shell specially designed to run these programs.  The
> shell could also contain a commonly-used subset of the CRT to save on
> storage (IE, the sheel would have 1 copy of printf() instead of 3
> programs each having identical copies).  This, to me, is the most
> interesting programming challenge, but perhaps not the most reasonable.

Nobody will use it... :-(

Programming in C is only better for the programmer. I don't expext an
influx of many great C written games/progs. (but okay, "640k should be ..")

C programs _will_ be bigger than normal handwritten asm. There won't be a
good reason to switch. Even if it would be much better (crash protection,
et all), not many people would use it, as proven before. <sigh />

>>> looks to me (after some simple tests) that as long as a "good" copy of
>>> IY is saved and restored before you call any system routines or exit
>>> the program, you can change IY all you want.
>>
>> And what about the system interrupt? You should disable that too,
>> shouldn't you?
> 
> Yes, I considered that.  In the end, it may turn out to be best to
> create some sort of interrupt wrapper, as was mentioned.  I don't yet
> know enough about the TI-83 internals to know exactly when and why
> interrupts are triggered (there seems to be no authoritative technical
> reference, just poorly written 'gurus' by people who don't understand the
> system well at all), but it seems to me so far that you may not need to
> worry about interrupts.

Yup, most interrupt tutorials are incorrect. Try looking at more recent
interrupt programs. Working interrupt programs often use working IM2
interrupts :-)

	Henk Poley <><