Jonah Cohen Releases Megacar v1.0
Posted by Eric on 30 December 2000, 19:22 GMT
Yup, that birds-eye-view racing game for the TI-89/92/92+ we've all grown to love is now available for the TI-86, thanks to Jonah Cohen. Megacar v1.0 for the TI-86 features black and white graphics, fast scrolling, high scores with initials, eight external levels, and an external Windows level editor made by Kirk Meyer. A Megacar levels directory will be created once enough people have uploaded levels. Thus, go check it out, and go make some levels too while you're at it. Update (Eric): Jonah has released Megacar v1.1, which updates the tileset so it'll match more accurately. If you're going to create your own external levels, be sure to download this upgrade!
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The comments below are written by ticalc.org visitors. Their views are not necessarily those of ticalc.org, and ticalc.org takes no responsibility for their content.
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Re: Jonah Cohen Releases Megacar v1.0
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muchodinero
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two words
hell yeah!!!!
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30 December 2000, 19:51 GMT
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Re: Re: Re: Re: Re: Re: Jonah Cohen Releases Megacar v1.0
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Dan Englender
(Web Page)
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Interesting. I wont argue that it would be a slight pain to get this game to work on the 83 Plus, but not for these reasons. Code running from Flash ROM runs at the same rate as code running from RAM. Otherwise the TIOS would have some trouble, not to mention applications, which are run directly from RAM. In the grand scheme of things running an application would probably be quicker than a RAM program since you don't have to do any relocation (of course, this isn't actually the case, since the TIOS does some wacky validation and certificate writing stuff when running applications).
Of course, no code would be running from Flash ROM anyhow, since programs are copied to RAM before they're run. And since the memory requirement in question is not for the program code, but for the data, it becomes a sort of mute point.
As for speed of writing to Flash, it actually doesn't take so much time to write to, it's just that you can't write to it. The TIOS does a good job of making sure you never directly write anything to Flash, so you either have to copy a program to RAM, modify it, and send it back to ROM, or just not modify it at all. Of course, the issue of data space is not related to the program modifying itself, so this doesn't matter.
As Kirk pointed out, the problem is that there's a lack of RAM space to decompress the levels to. I can't say that I've checked exactly how much is needed, but from what I hear it's quite a lot. That means you'd have to keep your RAM fairly clear so that levels could be decompressed. I suppose it's not too big of a problem since you all of that archive memory to keep programs in, but it could become inconvenient.
Depending on how the code is written, it would be possible to gain some memory back by fragmenting the program and relocating parts into free spots of memory. Generally this would be a waste of time, but the 83 Plus is really overflowing with fairly large blocks of memory which would never be used during program execution. There's nearly 3k of free space laying about (which doesn't being to compare with the 86...I know), and some more if you can bare direct writes to the screen. Since the memory is fragmented, it wouldn't help much with the data requirement, but some of space used for code that was moved there could then be used for data. Back to the original point, archive memory would be useful terms of holding the compressed levels (and would have nothing to do with program execution or speed), but you'd still need a bunch of free RAM. So basically, a port would be possible, though slightly annoying. Sorry for the long post.
(Oh, and a (not so) quick aside to that person who so eloquently asked why I'd be so stupid program for the 83(plus) and not other calculators...I do so because I like programming for it. Of course the TI-86 is more powerful, it was built that way. If all I wanted to do was be able to program for the most powerful platform, I'd be programming for a computer instead of a calculator. I like the challenge of having to work with limited resources. Of course, the fact that the TI-83 was my first calculator might have influenced my interests).
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1 January 2001, 07:51 GMT
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Re: Uses of Flash ROM
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Dan Englender
(Web Page)
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I very much doubt that this is the case. The Flash chip has high enough access times for code to run directly from it, so there's no reason to do otherwise. I don't think TI would waste the money to include yet memory buffer to load code from Flash into. Not to mention that either it would have to be 512K (very unlikely since there is only one 512K chip on the circut board, the Flash ROM chip) or the current mapped page would have to be loaded to this special cache, which would take much more time than a few clock cycles (you can read from a new flash page after a single output instruction, you don't have to wait for any delay for it to load). There's no way the ROM copies the Flash to a "system section of RAM", since the RAM is only 32K and all of that is accounted for very well.
I agree that the reason Flash is not used like RAM is that it has limited writes. That's why TI protects the chip (well, among other reasons). The Flash, however, has an unlimited number of reads, so there's no reason for code to be run from any other place.
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5 January 2001, 04:29 GMT
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