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TI-83 Plus Outputs TV
Posted by Michael on 30 November 2007, 21:46 GMT

Ben Ryves has accomplished one of the most amazing calculator hardware projects ever: Connecting his TI-83 Plus to a PAL television set. Details and photographs are available at the MaxCoderz forum. He is currently able to display a 304 line image, but with a faster 84+ calculator, resolution could increase. NTSC video should also be achievable. Congratulations to Ben for an amazing achievement!

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Re: TI-83 Plus Outputs TV
jean ghosn  Account Info
(Web Page)

Woah! I never imagined that calculators could be used for such an awesome feat! haha now we can watch the calculator (instead of TV) :P

Reply to this comment    30 November 2007, 22:15 GMT

Re: TI-83 Plus Outputs TV
elfprince13 Account Info
(Web Page)

holy hell
nice work ben.

Reply to this comment    1 December 2007, 00:43 GMT

Re: TI-83 Plus Outputs TV
bfr Account Info
(Web Page)

Woah, that's amazing. Great work!

Reply to this comment    1 December 2007, 06:34 GMT

Re: TI-83 Plus Outputs TV
Lewk Of Serthic  Account Info

Major congrats to Ben Ryves! Very awesome.

Reply to this comment    1 December 2007, 07:59 GMT

Re: TI-83 Plus Outputs TV
adriweb Account Info
(Web Page)

Wooow !!

CONGRATULATIONS BEN !!!!

It's just incredible !

Reply to this comment    1 December 2007, 08:41 GMT

Re: TI-83 Plus Outputs TV
Patrick Prendergast  Account Info

This is such an amazing achievement, great work Ben ... you're a bloody genius!

/me needs to go into town to buy a 5v regulator

Reply to this comment    1 December 2007, 12:40 GMT

Re: TI-83 Plus Outputs TV
Kevin Ouellet Account Info
(Web Page)

ew that friggin sucks, the author need to die by watching american idol

j/k awesome work, at least maybe one day we will be able to play our games on huge screens without having to use emulators like VTI, PTI, wabbitemu and tilem

Reply to this comment    1 December 2007, 21:49 GMT

Re: TI-83 Plus Outputs TV
Mr.Z  Account Info
(Web Page)

Huh...I tried this once before. I wrote a similar program & connected my TI-86 to my NTSC TV, but it would not sync correctly. Since I had the timings very close (they worked in the prototype I wrote in Visual Basic using the timestamp counter), I assumed it was just because my batteries were low. It would really help if the calculators had clock crystals instead of RC oscillators.

Glad to hear someone got it to work better, though I hope it works in NTSC & not just PAL.

Reply to this comment    2 December 2007, 16:24 GMT

Re: Re: TI-83 Plus Outputs TV
Michael Vincent  Account Info
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The 83+ SE and 84+ do have crystal timers, with interrupt capability. It would make this work much better.

Reply to this comment    3 December 2007, 01:26 GMT


Re: Re: Re: TI-83 Plus Outputs TV
Mr.Z  Account Info
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Oh, well, then that does help. :)

Reply to this comment    3 December 2007, 20:29 GMT


Re: Re: TI-83 Plus Outputs TV
Mr.Z  Account Info
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Come to think of it, the NTSC standard seems to be pretty lax about the overall timings (as evidenced by the success of my Visual Basic-based TV signal generator), so I must have gotten the sync pulses wrong or something.

Reply to this comment    6 December 2007, 22:34 GMT

Re: TI-83 Plus Outputs TV
benryves  Account Info
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Thank you for the feature. :)

As Michael Vincent pointed out (and as is discussed in the MaxCoderz thread) this would probably work a lot better on an SE or higher, not only for the increased horizontal resolution but so one might use the interrupt timing to leave some CPU time for a game.

Reply to this comment    3 December 2007, 12:50 GMT

Re: TI-83 Plus Outputs TV
DWedit  Account Info
(Web Page)

You know what other system made the programmer manually generate a TV picture? The ATARI 2600!
(okay, not really, but its video chip was so primitive that you basically had to draw each scanline to the video chip as the screen redrew!)

Reply to this comment    4 December 2007, 02:38 GMT


Re: Re: TI-83 Plus Outputs TV
Rick Skrbina Rick Skrbna  Account Info

dont you have to redraw every scanline to the video chip on as the screen redraws on any system?

Reply to this comment    9 December 2007, 22:15 GMT


Re: Re: Re: TI-83 Plus Outputs TV
Mr.Z  Account Info
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Many systems have framebuffers. I am not familiar with the Atari, but it is possible that it had no framebuffer, just a video generator attached through DACs to the data lines.

Reply to this comment    10 December 2007, 16:21 GMT

Re: Re: Re: Re: TI-83 Plus Outputs TV
Rick Skrbina Rick Skrbna  Account Info

the atari 2600 does not have a frame buffer, and that is the only system i program for, so i am not familiar with frame buffers. on the atari, to make playfeilds (the background) not a mirror image of itself (left side mirrored to right) you have to count machine cycles until the electron beam has reached the center of the screen and then change the values of the video chip (TIA) registers.

A frame buffer sounds very helpful!

Reply to this comment    11 December 2007, 20:28 GMT


Re: Re: Re: Re: TI-83 Plus Outputs TV
benryves  Account Info
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Framebuffers are very expensive (memory-wise) so older hardware will typically use a certain number of tiles (or "characters") and use tilemapped displays. There often isn't enough VRAM to store one tile per tilemap entry, which can make simulating bitmapped displays rather difficult.

Reply to this comment    12 December 2007, 10:37 GMT


Re: Re: Re: Re: Re: TI-83 Plus Outputs TV
Mr.Z  Account Info
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I have heard of tilemapping, but for some reason that did not come to mind when answering the question. Oh, well.

Reply to this comment    19 December 2007, 14:43 GMT

Re: TI-83 Plus Outputs TV
El_Diablo  Account Info
(Web Page)

This is cool, but I still prefer the projector screen, it's bigger and compatible with my 89 TI.
But now I can get away from the emulator mess on the computer!

Reply to this comment    5 December 2007, 18:20 GMT


Re: Re: TI-83 Plus Outputs TV
Michael Vincent  Account Info
(Web Page)

It would be interesting if somehow the full 96x64 monochrome output could be viewed, and done via interrupts, so that normal OS operation were possible. Someone could then sell very cheap ways to view a calculator on a TV system and perhaps make a fortune selling to schools in place of the expensive TI systems.

Reply to this comment    6 December 2007, 00:47 GMT


Re: Re: Re: TI-83 Plus Outputs TV
Mr.Z  Account Info
(Web Page)

Well, if you used an external chip to generate the signal (including some form of buffering, since the data would come in bursts during interrupts), you could output a single frame (on the TI-83+) using 173,553 clock cycles (including the conversion to 2-bits-per-output), yielding 86.4FPS at 15MHz (TI-83+SE/84+(SE) speed). If you limit the framerate to 50FPS, then you get around 6.3MHz left over for the OS, or plain TI-83+ speed. Sounds doable, but it needs an FPGA or microcontroller.

Reply to this comment    6 December 2007, 03:05 GMT

Re: Re: Re: Re: TI-83 Plus Outputs TV
Mr.Z  Account Info
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Read that as "on the TI-83+ SE." Of course, you could always just lower the framerate on a plain TI-83+ or a TI-86, but with significant OS/game slowdown.

Reply to this comment    6 December 2007, 03:07 GMT


Re: Re: Re: Re: Re: TI-83 Plus Outputs TV
El_Diablo  Account Info
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I doubt a greyscale game like Desolate for the 83/84 would work right with this set up though... Anyone try it?

Reply to this comment    6 December 2007, 14:07 GMT


Re: Re: Re: Re: Re: Re: TI-83 Plus Outputs TV
KermMartian  Account Info
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There's no doubt it wouldn't work off the bat, but some modification of the code routines could certainly be plausible...

Reply to this comment    6 December 2007, 19:46 GMT


Re: Re: Re: Re: TI-83 Plus Outputs TV
Mr.Z  Account Info
(Web Page)

Here is the code I used for the above timing (if anyone cares). Let p be the link port. Also, HL should be loaded with the address of the data to output & B with the count. Set B to 0 & repeat the code 3 times to copy enough bytes for a 96x64 bitmap. Put a table at XX00..XX03 of the link values to transfer 00, 10, 01, & 11 (respectively) & load D with XX.

LOOP: / LD C,(HL) / INC HL
[REPEAT 4x]
XOR A / RRC C / RLCA / RRC C / RLCA
LD E,A / LD A,(DE) / OUT (p),A
[END REPEAT]
DJNZ LOOP

Reply to this comment    6 December 2007, 22:23 GMT

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