Author Topic: A new z80 calc... in color?  (Read 45642 times)

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Offline DJ Omnimaga

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Re: A new z80 calc... in color?
« Reply #105 on: November 09, 2012, 09:02:20 pm »
I hope they make it a double-buffered display for BASIC and graphing.
What would be double-buffering in that case? Do you mean it would be faster to switch between screens or do you mean split screen? I personally don't want BASIC games to be windowed like in TI-Nspire BASIC D:

Also if it's built on top of Nucleus and kinda partially emulated, I hope that TI won't use a slower ARM processor, because then TI-BASIC will be even slower than on a 84+. X.x (in 84+ mode on the Nspire, if you have OS 2.0 or higher, the speed is exactly the same as a real TI-84+). Remember what happened to Casio BASIC on the PRIZM? D: (Although I seriously doubt it will deteriorate that drastically on TI's new color calc)

Offline willrandship

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Re: A new z80 calc... in color?
« Reply #106 on: November 09, 2012, 11:38:10 pm »
Have no fear, DJ. Double buffering has nothing to do with split screens.

LCD displays require dedicated RAM to store their current image. This is their first buffer. Single-buffered drawing writes directly to it. However, since this involves dealing with the display controller, it's slower than normal RAM access, and it results in screen flickering.

In Axe, and most Assembly programs, we use a 'double buffer' which is simply a copy of what will be displayed stored in RAM. This is copied over once all drawing actions on it are finished, resulting in only one slow copy, rather than one for every action.

TIOS, however, is even worse: It runs a double buffer setup, but it copies it to the single buffer every time it does a drawing action. Since these drawing actions are very small (well, except bitmap) the resulting performance is as bad as a single-buffer solution in every way, but also takes up the extra RAM of a double buffer solution.

The best place to see this in action is in TI's apps, like the periodic table. You can see each line being drawn, with significant delay. A double-buffered display would draw it in RAM, then copy the picture over to the display RAM, resulting in a far smoother application.


And yes, it would be terrible if they make no improvements and just use the old emulator plus some color.
« Last Edit: November 09, 2012, 11:38:50 pm by willrandship »

Offline DJ Omnimaga

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Re: A new z80 calc... in color?
« Reply #107 on: November 10, 2012, 12:14:43 am »
Also TI-OS routines are slow to display stuff in the first place. No wonder why some ASM/Axe coders use custom font routines x.x

Offline ralphdspam

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Re: A new z80 calc... in color?
« Reply #108 on: November 10, 2012, 12:15:35 am »
If this is an ARM processor, I can't wait to see how long it would take to hack the Nspire OS onto it.

That would be a terrible waste to make it an emulator for its opperation.  I really hope it has an eZ80 core.  The faster clock speed and single-cycle instruction execution would be a great enhancement to existing assembly programs.

Let's hope they don't mess this up.
« Last Edit: November 10, 2012, 12:16:07 am by ralphdspam »
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Offline DJ Omnimaga

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Re: A new z80 calc... in color?
« Reply #109 on: November 10, 2012, 12:21:28 am »
Well an emulator is plausible, given TI record on being kinda lazy  (eg: how they used a pre-made software for most of the Nspire OS and did not bother removing unused stuff). If it's really an emulator, I wouldn't be surprised if we found Nspire OS leftovers in the OS disassembly.

Also nice to see you around Ralph :D

Offline willrandship

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Re: A new z80 calc... in color?
« Reply #110 on: November 10, 2012, 01:08:49 am »
There's pretty much no chance of the ez80, since AFAICT Texas Instruments never licensed it from zilog. In fact, it doesn't look like anyone did.

It would be really cool if we could get the nspire CAS OS running on this thing. The keys would be wrong, but the CAS touchpad OS never complained about using an 84+ keypad.

Offline calc84maniac

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Re: A new z80 calc... in color?
« Reply #111 on: November 10, 2012, 01:15:29 am »
Considering how cheap they are, I doubt they'd put that much RAM in this thing (128KB -> 48KB anyone?), even if it is identical to the Nspire hardware in every other way (which we also can't assume).
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Offline willrandship

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Re: A new z80 calc... in color?
« Reply #112 on: November 10, 2012, 02:07:59 am »
Well, I wouldn't be surprised to see the old 32MB RAM chips from the old nspire in it, or maybe a bit lower. I don't think the 84+ emu could run in RAM amounts too much lower, though.

Offline DJ Omnimaga

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Re: A new z80 calc... in color?
« Reply #113 on: November 10, 2012, 04:08:06 am »
Considering how cheap they are, I doubt they'd put that much RAM in this thing (128KB -> 48KB anyone?), even if it is identical to the Nspire hardware in every other way (which we also can't assume).
Although they have to do something about the screen. I don't think people will like if their 8xi images take the entire RAM.

Offline willrandship

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Re: A new z80 calc... in color?
« Reply #114 on: November 10, 2012, 08:02:34 am »
Who knows, maybe the 8xi images will stay at the lower resolution X.x

Offline Adriweb

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Re: A new z80 calc... in color?
« Reply #115 on: November 10, 2012, 09:49:27 am »
Hey, maybe someone wants to put it as news, i'm not sure ? If so, just tell me , I'll copy/paste

But anyway, I've made a history of how the 84C got discovered etc. :
http://tiplanet.org/forum/viewtopic.php?lang=en&p=132106#p132106

(French + English ;) )


EDIT : I've been advised that it can go to news :P http://ourl.ca/17436.new#new
« Last Edit: November 10, 2012, 09:53:54 am by adriweb »
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Offline TIfanx1999

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Re: A new z80 calc... in color?
« Reply #116 on: November 10, 2012, 11:32:15 am »
Although it's unlikely, I'd love for this thing to be running an EZ80. :D Larger screen res. and more memory would be great as well... For those of you saying a normal Z80 with color wouldn't be that great I'd like to remind you that many older computers(MSX, ZX Spectrum) and game systems (Gameboy color, Sega Master System/Game Gear) Used Z80's and had color.

Offline Keoni29

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Re: A new z80 calc... in color?
« Reply #117 on: November 10, 2012, 11:34:57 am »
Yes, but they had a lower resolution.
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Offline Sorunome

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Re: A new z80 calc... in color?
« Reply #118 on: November 10, 2012, 12:03:11 pm »
I hope that everything will still be possible and that they emulate the pixels of the 84+ well :D
And to the pictures, maybe they are adding a new data format for color ones and both works then?

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Offline ralphdspam

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Re: A new z80 calc... in color?
« Reply #119 on: November 10, 2012, 12:50:24 pm »
Please also be mindful that the older color systems with z80 hardware were not full color; hardware sprites or tiles could only have a few colors at a time.  This artifact can be easily seen in "attribute clashing" of the ZX Spectrum graphics.  In the Sega MasterSystem/GameGear and MSX, Texas Instruments' TMS9918 IC made these artifacts less apparent with the use of movable sprites. 

[I lied.  The TMS9918 does in fact have a rarely used mode that would map a single color to each pixel, but it had drawbacks in resolution.]

I assume from the picture that TI is not using a tiling method to display color on their screen.  Mapping one color per pixel is much more CPU intensive.

EDIT: Maybe not too intensive if they use a good DMA.
« Last Edit: November 10, 2012, 12:52:26 pm by ralphdspam »
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