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Andy Selle Releases SpaceWar Source Code
Posted by Nathan on 17 September 2003, 00:16 GMT

Andy Selle released the source code to his game SpaceWar on Friday. This was one of the early ZShell programs. For those of you who may not have been around at the time, ZShell was the very first assembler shell written for the TI-85 calculator. At this time, TI did not have any sort of ASM support, and a loophole was found in the TI-OS which allowed arbitrary code to run. By installing a modified backup file, you could install ZShell, which then provided ASM support to other ASM programs on your calculator.

This is a fun little game that has link support between two calculators. It's not the most impressive or advanced game, but it is indeed a piece of history which still has a place deep in the heart of many people who were around back in 1996, like me.

 


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Re: Andy Selle Releases SpaceWar Source Code
tifreak8x  Account Info
(Web Page)

Well, since things are already off topic...

I was wondering if there was anyone who could help me understand the 89 Matrix. If someone could help me, please email me.

Annuncer: And now back to our regular program...

     20 September 2003, 15:01 GMT


Re: Re: Andy Selle Releases SpaceWar Source Code
no_one_2000_  Account Info
(Web Page)

The movie or the math matrices? :)

Um... just use the same syntax that you would for any other calc model.

[[1,2,3][4,5,6][7,8,9]]

is the same as: (use a monospaced font, like in Notepad)

[[1 2 3]
[4 5 6]
[7 8 9]]

The only difference: don't try to store them to something like [A]. Use a regular variable name. [[1,2,3][4,5,6][7,8,9]]->mymtrx (and the ->, of course, is the store command)

There is, however, a data/matrix editor, that may help you save time, without typing everything in on the homescreen in that format.

Uh, hope that helps...

     20 September 2003, 16:31 GMT


Re: Re: Re: Andy Selle Releases SpaceWar Source Code
tifreak8x  Account Info
(Web Page)

That is not what I was talking about. If you look at the Pokemon game, he uses matrices to place the pics. 'a10073pallet2' is an example of what I am saying. He uses the matrices to place pics on the screen, and uses another matrix for hit detection (i think). I want to make AOD on to the 89 with graphics...

     20 September 2003, 20:27 GMT


Re: Re: Re: Re: Andy Selle Releases SpaceWar Source Code
no_one_2000_  Account Info
(Web Page)

Ooooh... well, the TI-89 can save actual pic files, so wouldn't that be easier than using matrices? I think that it would be faster, too. I dunno... I'd just go and use C. It's MUCH faster, and it's about as easy as TI-BASIC. (I understand C more than TI-BASIC(89), anyway)

     21 September 2003, 17:20 GMT


Re: Re: Re: Re: Re: Andy Selle Releases SpaceWar Source Code
tifreak8x  Account Info
(Web Page)

lol. i might go look for a tutorial on learning C then. It might be easier that way...

     21 September 2003, 22:30 GMT

ZShell
neo88 Account Info

Can anyone fill me in on what the heck ZShell is? As technically as you can please.
Thanks

     23 September 2003, 23:06 GMT


Re: ZShell
Eugene Talagrand Account Info

ZShell was the program that allowed people to run Assembly programs on the TI85. The TI85 was the first calculator for which assembly programming was discovered, before TI officially started supporting assembly.
It was discovered that entries in the custom menu could make execution jump to anywhere in memory. Modified backups for the TI85 installed and entry into the custom menu that would allow to jump to a specified address. Early hackers would save their programs as bitmaps and load them to the screen memory before jumping to the screen memory for execution (a huge hack needless to say).
In a ZShell modified backup, ZShell would be stored starting the first byte of user memory, hence its memory address was constant and reliable. Once ZShell was loaded, it would scan memory for assembly programs (stored as character strings - basically binary data - with a special format) and would allow to jump to their memory address. ZShell also provided a Rom-call lookup table for supporting different versions of the ROM. I think some later shells would actually move memory around and relocate programs to a fixed memory address (usually 0+shell size) to allow for absolute jumping and memory manipulation within a program.

ZShell was later superceded by Usgard, which is a backwards-compatible (in the standard version) shell.

But I think Magnus would best answer this question as he was one of the developpers and is one of the few (the only?) detainers of the never-released ZShell 4.5

     26 September 2003, 09:38 GMT
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