TI-Nspire CX CR4 (hardware revision W+) infos

[critor]

Some little topic on the new TI-Nspire CX CR4 hardware.
(hardware revision W+ manufactured since November 2015)

New screen, with a new buffer geometry.
The new buffer is 90° rotated making it 240x320 instead of 320x240, and mirrored.
To give you an idea, if you run on a CR4 some code which does not support the new screen it looks like this :

Therefore, TI just completely broke the compatibility with all existing Ndless programs - diabolically brilliant.
So either we will have to rebuild all existing Ndless programs, most authors having moved on, and for some of which the source code is not available...
Either a future CR4 Ndless could have some kind of a compatibility layer...
But even in the latter case, it would imply writing the screen buffer two times (normal writing of the original program + fix writing), and so it would have a high performance cost for programs constantly refreshing the screen (nDoom, nQuake, emulators...) - we can expect a halving of the fps if there is no CR4 update.

As a result, natural antidowngrade protection: OS / Boot2 / Diags versions 4.0.0 and earlier will not work properly.
Versions 4.0.1 or newer are mandatory.

The CR4 therefore obviously comes with a new Diags, the CR CX IV DVT (2015/06/08) Diag in Version 4.0.1.45 built on August 18 , 2015.


New boot1 as already stated, version 4.0.1.43 built on July 20, 2015.
Here the bootlog:

Code: [Select]

Boot Loader Stage 1 (4.0.1.43)
Build: 2015/7/20, 14:47:25
Copyright (c) 2006-2015 Texas Instruments Incorporated
Using production keys

Last boot progress: 0

Available system memory: 28072
Checking for NAND: NAND Flash ID: Generic 1 GBit (0xA1)
SDRAM size: 64 MB
Wakeup Event: ON.
SDRAM memory test:   Pass
Clearing SDRAM...Done.
Clocks:  CPU = 156MHz   AHB = 78MHz   APB = 39MHz   
Clearing SDRAM...Done.
Boot option: Normal

Loading from BOOT2 partition...

100%

BOOT1: loading complete (168 ticks), launching <BOOT2> image..

According to the new Boot1 log, the new TI-Nspire CX CR4 are faster as slightly overclocked:
156MHz instead of 132MHz - and therefore a 18% speed increase !

Boot1 also has a new boot combo : [doc][enter][1] allowing to reflash the Manuf partition with an RS232 sent image.
Perhaps finally a way to repair TI-Nspire CX calculators whose Manuf has been damaged.

[xlibman]

Interesting, especially the screen. Does it mean that the calc uses the same screen as the TI-84 Plus C Silver Edition, but larger? On the CSE, you can notice vertical scanlines if you stare at the screen, which are normally horizontal on other calcs.

This sucks for all Ndless programs, though. I hope that TI did that mainly to improve performances, to save on production costs or to replace a no-longer-produced part, and not as another attempt to block Ndless programs. A compatibility layer will definitively have to be written, even if it means that all programs run much slower (in which case, people might as well switch to Lua or HP PPL). Casio did that with the SH4 calcs, which broke compatibility with many ASM programs.

I wonder if the new screen could have touchscreen capabilities in future Nspire updates? I also hope that the new Boot1 is indeed safer against calculator bricking.

[Ivoah]

New screen, with a new buffer geometry.
The new buffer is 90° rotated making it 240x320 instead of 320x240, and mirrored.
To give you an idea, if you run on a CR4 some code which does not support the new screen it looks like this :

Therefore, TI just completely broke the compatibility with all existing Ndless programs - diabolically brilliant.
So either we will have to rebuild all existing Ndless programs, most authors having moved on, and for some of which the source code is not available...
Either a future CR4 Ndless could have some kind of a compatibility layer...
But even in the latter case, it would imply writing the screen buffer two times (normal writing of the original program + fix writing), and so it would have a high performance cost for programs constantly refreshing the screen (nDoom, nQuake, emulators...) - we can expect a halving of the fps if there is no CR4 update.

Oh goodness. That's horrible. Is there any other reason they might have made the switch, or is it solely to screw Ndless?

[Vogtinator]

Interesting, especially the screen. Does it mean that the calc uses the same screen as the TI-84 Plus C Silver Edition, but larger? On the CSE, you can notice vertical scanlines if you stare at the screen, which are normally horizontal on other calcs.

It's likely the exact same model, which makes sense, economically.

This sucks for all Ndless programs, though. I hope that TI did that mainly to improve performances, to save on production costs or to replace a no-longer-produced part, and not as another attempt to block Ndless programs. A compatibility layer will definitively have to be written, even if it means that all programs run much slower (in which case, people might as well switch to Lua or HP PPL). Casio did that with the SH4 calcs, which broke compatibility with many ASM programs.

As can be seen in the boot log:

Code: [Select]

Clocks:  CPU = 156MHz   AHB = 78MHz   APB = 39MHzSo it's overclocked (or a higher default clock) by default
TI had to embed a compatibility layer for the new LCD themselves, a new OS task "DispCpy" converts the framebuffer in a fixed interval,
which is exactly how the ndless compatibility layer is going to work. (Together with some MMU, timer and FIQ trickery...)

[xlibman]

What was the default clock speeds in hardware J? I forgot. Wasn't it 132 or 120 MHz CPU speed?

And wow, if even the OS uses a compatibility layer, then does that mean that the new calc will actually run slower despite the overclocking?

[Adriweb]

Oh goodness. That's horrible. Is there any other reason they might have made the switch, or is it solely to screw Ndless?

It pretty much doesn't have anything to do with Ndless (although I'm sure TI is happy about this side-effect ). Remember that "CR4" stands for "Cost Reduction" (phase 4).
So, one way or the other, this LCD was probably cheaper than the old one, the only actual downside being some software tricks to compensate for the orientation/mirror/rotation.

And wow, if even the OS uses a compatibility layer, then does that mean that the new calc will actually run slower despite the overclocking?

My guess is that they overclocked it as fast as they needed to in order to have the calc behave the same way as older HW. So, there will probably be no visible difference for users.
We may wonder about battery usage, though, but since they've been also messing with power-related stuff in CR revisions, maybe they've improved that to make up for the loss

[critor]

What was the default clock speeds in hardware J? I forgot. Wasn't it 132 or 120 MHz CPU speed?

132MHz for all CX up to hardware V.
120MHz was on older TouchPad/ClickPad.

[Snektron]

Isn't the first of april still like a month away?

[xlibman]

What was the default clock speeds in hardware J? I forgot. Wasn't it 132 or 120 MHz CPU speed?

132MHz for all CX up to hardware V.
120MHz was on older TouchPad/ClickPad.

I thought that ClickPad calcs were 90 MHz? Or was it just for OS 1.1 through 1.7?

Isn't the first of april still like a month away?

Sadly, this is not an early april fools joke D:

[critor]

What was the default clock speeds in hardware J? I forgot. Wasn't it 132 or 120 MHz CPU speed?

132MHz for all CX up to hardware V.
120MHz was on older TouchPad/ClickPad.

I thought that ClickPad calcs were 90 MHz? Or was it just for OS 1.1 through 1.7?

Yes. Starting with 2.0 they're overclocked to 120MHz.

[aeTIos]

Remember that "CR4" stands for "Cost Reduction" (phase 4).

I'm sure this doesn't imply a cheaper cost for end users
But yeah, that sucks balls man. 50% speed loss... That's the end for most games

[critor]

50% speed loss for some games, only if they don't get updated with CR4 screen support.

[aeTIos]

Ah, I see. That makes it a bit less bad, but still bad, mainly because gbc4nspire's source code was lost. At least gpsp-nspire can be updated.

[catastropher]

This really sucks I love TI for making the calculators, but I really hate them for the way they treat the community...

[xlibman]

50% speed loss for some games, only if they don't get updated with CR4 screen support.

What if the compatibility layer has frame skipping?