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Messages - Goplat

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TI-Nspire / Re: Would an NES emulator be possible on Nspire?
« on: January 19, 2012, 04:00:11 pm »
Here is a CX compatible version. I also added a 'B' option to toggle the border between white and black, since many NES games use dark backgrounds, and with a backlit screen like the CX's a black border might look better in this case.

TI-Nspire / Re: TI-Nspire emulator
« on: January 19, 2012, 04:00:06 pm »
Here is the version capable of emulating the CX. Use the /M switch to specify the model of calculator to emulate:
/MC for CAS
/MX for CX
/MM for CM
For the CX/CM models, you can change the size of SDRAM to 64MB with the /R switch, and the size of NAND flash to 128MB with /N. (Both options are off by default just because they use a lot of memory and most programs won't need them)

This talk of creating a censor-proof 'shadow internet' sounds a lot like I2P.

News / Re: Even more early TI-Nspire prototype discovery
« on: January 14, 2012, 09:49:06 pm »
it might want a signal over serial to trigger it. Just a thought.
Good point. Looking at the U-Boot source code, both input and output default to serial (and it's unlikely TI would change the input to be the calc keypad while leaving the output as is).

News / Re: Even more early TI-Nspire prototype discovery
« on: January 14, 2012, 03:33:37 pm »
Hit any key to stop autoboot:  0
Is it possible to press a key before this counts down to 0, and get into the U-Boot Monitor shell? It has a command md addr len to display memory contents. There also may be a command nand read addr ofs size to read NAND flash into memory (also nand read.oob addr off size to read the extra "out-of-band" 16 bytes per page)

Edit: Unfortunately TI probably set the delay to 0 seconds, which would make it impossible unless CONFIG_ZERO_BOOTDELAY_CHECK is defined (and it isn't in the default include/configs/omap5912osk.h)

TI-Nspire / CyberBox
« on: December 27, 2011, 09:23:55 pm »
I wrote this clone of the DOS game CyberBox back in April, but never got around to putting in the finishing touches and releasing it.

Calculator C / Re: Hide documents on TI-Nspire [Ndless]
« on: December 26, 2011, 12:00:43 pm »
The screen will be cleared on program startup on CX in the next update to avoid this (the documents screen cannot be displayed in grayscale).
IMO, Ndless shouldn't switch to grayscale mode at all. Old pre-CX programs won't work on the CX without a rebuild anyway, so there's no backward compatibility reason to do so. I expect most CX programmers will want to use color when available.

Other Calculators / Re: Interesting TI-84+ Screen Behavior
« on: December 13, 2011, 03:12:07 am »
Quote from: Wikipedia
STN LCDs have to be continuously refreshed by alternating pulsed voltages of one polarity during one frame and pulses of opposite polarity during the next frame.

The T6A04 used does just that, and so do all other controllers for this kind of LCD. And for good reason:

Quote from: TI OMAP5910 documentation
This pin is used to periodically invert the polarity of the power supply to prevent dc charge build-up within the display.
Quote from: ARM PL110 documentation
STN displays, which require the pixel voltage polarity to be periodically reversed to prevent damage due to DC charge accumulation
Quote from: Atmel AVR065 application note
The LCD must be driven by alternating current (AC). Direct current (DC) will cause electrophoresis effects in the liquid crystal and will degrade the display.
Quote from: Panasonic EDMGRB8KJF requirements
ON/OFF of Power Supply and Signal - Driving liquid crystal molecular by DC current may cause serious damages to LCD including disorder of alignment and electrical decomposition.
Quote from: Maxim MAX1677 application note
The contrast voltages must be symmetric about VM to avoid a DC component across the liquid crystal, which in turn would damage the LCD or shorten its life.

Alternating pixels between black and white at the same speed as the LCD controller alternates between positive and negative voltages means that those pixels receive only the positive pulses or only the negative pulses, effectively creating direct current just like the controller is supposed to prevent.
In summary: Don't use this effect unless you want to screw up your screen.

News / Re: Ndless 3 Alpha on Nspire CX CAS (photos + video)
« on: December 03, 2011, 08:32:02 pm »
Code: [Select]
unsigned short (*buffer)[320] = *(unsigned short (**)[320])0xC0000010;and then individual pixels are accessible with buffer[y][x]. It's not too common to have a pointer-to-array in C, but it is legal :)

Other Calculators / Re: Ndless 3.1 alpha testing has just begun
« on: November 27, 2011, 02:41:23 pm »
It's the same hardware, it's just that non-CX OSes don't enable it.

Other Calculators / Re: Ndless 3.1 alpha testing has just begun
« on: November 27, 2011, 02:33:58 pm »
(not yet compatible with CX, sorry)
BalancedFury, not so. Part of the problem, as I recall, is a piece of the CX hardware meant to prevent things like Ndless.

Is this about the watchdog timer? That's pretty easy to defeat:
*90060C00 = 0x1ACCE551
*90060008 = 0
*90060C00 = 0
will turn it off.

Ndless / Re: Ndless 1.7 for TI-Nspire
« on: November 22, 2011, 06:35:53 pm »
Get a needle or something similar, press the reset-button at the back with it, while keeping it pressed down press Doc+Enter+EE, then while keeping these pressed release the reset-button and hold these three until the maintenance menu appears. Then just delete the OS and install another.

Note that on the Touchpad you have to press "T" to select option 2 from the maintenance menu.

« on: November 13, 2011, 01:45:13 pm »
The 1970s pong consoles weren't programmable; everything was done in hardware. So "emulating" one would just mean writing a pong game. :p

« on: November 10, 2011, 02:03:49 pm »
@AOC, I'm sorry, the 2600 was the first one they released, didn't look good enough. The 6502 processor is pretty easy to emulate, but I also just realized that I can't have a good clock in Lua, the fastest I would have would be 100Hz :(
Most emulators only synchronize emulated time with real time once per frame; 60Hz suffices for that.

The real problem is that Lua just wouldn't be fast enough to run 1/60 second of emulated time in less than 1/60 second of real time.

« on: November 10, 2011, 12:35:00 pm »
Let's compare Lua to Javascript: People have written NES emulators in Javascript, and they are slow even on a modern PC. The TI-Nspire has a much slower processor than a PC, and Lua is even less suited for emulation than Javascript; it not only has the big problem of not having typed variables (any variable in JS or Lua can point to an object of any type, so the runtime has to do a type check on every operation), but also doesn't even seem to have bitwise operators (which are used extensively in emulators and are inefficient to build out of other operators).

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