EDIT: I decided to turn this into a thread to talk about prototypes more in-depth since I have quite a few now.

As some of you might already be aware from the tiplanet thread, I found and bought a TI-Nspire CX II CAS prototype (DVT1.1). Normally I'd post this type of thing in the collections thread, but I think this warrants its own topic.




Stating the obvious, its in an old CX CAS case, and there is a piece of paper taped to the back that reads "Aladdin 1.1", Aladdin being the codename for the CX2 series. It also has DVT1.1 CD handwritten on the protective tape under the battery. I have no clue what the "CD" stands for, perhaps someone from TI-Planet might know.
It is in the 'DVT' phase of development as indicated by its serial Number (DVT1100033). It arrived a few days ago and I took a look inside. From the ebay listing, I could see that it was running a CX2 OS because the main menu said "Browse" as opposed to "My Documents". Since the new CX2 OS will only run on CX2 hardware, we already knew it would contain some new hardware. That being said, the inside was rather uninteresting because it was nearly identical to the first mass production CX II boards (revision AE). It was produced in July 2018, which is a few months before the MPs were produced (November 2018) and it contained some hand-written markings, but all major components were the same. This isn't very surprising since the MB labels on MPs contain "DVT", implying that they stem from this phase of prototyping. Unlike the MP models, the more eagle-eyed among you might have noticed that this one has 2 holes drilled into the front of the case which allow easy access to the screws that are normally tucked under the screen cover and require carefully unglueing the front of the calculator to access. This makes disassembly much easier, although like with all Nspire CX, its still not built to be taken apart :LOL:
The software is where things got more interesting, it is running an earlier build than the first production models (5.0.0.1407 as opposed to 5.0.0.1683).
Currently, we know of a few CX IIs produced before MP:

DVT2000175 5.0.0.1288 (T3IC 2019)
DVT1100033 5.0.0.1407 (Mine)
CX II-T CAS Samples from Didacta 5.0.0.1450
MS043 5.0.0.1500 (Didacta)
MS001 5.0.0.1500 (Didacta)
DVT2000211 5.0.0.1500 (Didacta)
DVT-EUR-0032 5.0.0.1624 (Didacta)
DVT-EUR-0190 5.0.0.1624 (Didacta)
Ti-Planet Samples 5.0.0.1509

EDIT (3 new protos with 3 new builds!):

DVT0000031 5.0.0.1359 (Mine)
DVT0000194 5.0.0.1395 (Ti64CLi)
DVT10000088 5.0.0.1372 (Mine)

It is earlier than the samples given out to TI-Planet back when the CX2 series was being released, and earlier than the marketing samples spotted at some conferences last year, However, it is newer than one prototype (labelled 'DVT2') also spotted at one of the European conferences, but that one is of course, not in the possession of anyone in the community. Again, this isn't really surprising since during the DVT phase is generally where a lot of software testing, quality assurance and development takes place, so it should be expected that TI went through a lot of builds in this phase. The boot loader is slightly earlier than the first production models, (5.0.0.82 as opposed to 5.0.0.89).
The one I've acquired seems to be the only one known that hasn't been polished into a pretty case, meaning it was almost certainly actually used for development, rather than marketing. Before anyone asks, I already took a look at the seller on ebay, and it seems to be a wholesaler who buys and sells thousands of random items, so they likely acquired it elsewhere and re-sold it.
Last year, there were some TI-Nspire CXs that were spotted fitted into CX2 cases on ebay which were probably made just as showpieces for conferences. This one is actually the opposite, it is a CX2 CAS fitted into a CX CAS case.

I am in contact with the guys from TI-Planet to try to get a dump. Critor noted that it doesn't have any "Dev unit" mention in the top left corner as it boots up, indicating that it verifies the OS with production keys rather than dev keys. Here is a link to his article about it, and here is a link to my tiplanet album containing some more images.

I've acquired 2 new TI-89 prototypes today.



These seem to be very early prototypes because the ASICs are dated 9644, more than a year and a half before the official release in July 1998. That being said, I believe these were manufactured in either January or February 1998, only about 6 months before the launch. They seem to have been produced approximately 3 weeks apart. The older one has a gray faceplate with white lettering, which is what prompted me to purchase the lot in the first place (It is black with white lettering on production models). The newer one has the regular black faceplate. Neither of them have serial numbers, and they both have an odd wire sticking out of the backup battery compartment. This wire leads to a resistor (R45) inside. This would allow them to play with the resistance by adding another resistor in series, but I'm not sure why they would want to do that, maybe a pull-up or pull-down resistor.... They both have a different silkscreen than the production models, with the lettering more centered.



This seems to be the same silkscreening as what's on promotional items like the posters that were sold with ViewScreens and in the guidebook.


They both have ROM versions that weren't discovered and that weren't released in mass production. The older one has 1.02 (09-30-1998) and the newer one 1.00b8 (07-02-1998). 1.00b8 is also the oldest ROM version to date, with the oldest one in mass production being dated 07-27-1998. They also both contain previously undiscovered boot code versions. The older one is 1.04b12 and the newer one is 1.00b4.



You may have noticed that the older one has a blue on green LCD while the newer one is black. I suspect it comes from the old TI-92 LCDs which were also blue on green, from which the TI-89 was heavily inspired. Both board revisions are also undiscovered, 9896MB-40F on the old one and 9896MB-40G on the newer one.


EDIT: Critor just posted a news article about the "newer one" over on tiplanet. He mentions that it is the oldest one found to date, which is true of the OS and boot code but not of the hardware, hence why I call it the "newer one".
EDIT2: Critor just posted another news article about the "older one" this time.

The silkscreening on the keys of those TI-89s looks rather close to a TI-73, and both have the arrow keys of a TI-73 instead of those of a production TI-89. The earlier TI-89's display and age put it closer to a TI-92 II than a TI-92 Plus, and both housings look to be the same color as a TI-92. Poking at the IC date codes puts them around the first month of 1998. The CPUs are older than the rest of the calculator, which makes sense because HW1 TI-89s use the same CPU as the TI-92. I feel like I've seen that white-on-green model number on another prototype calculator before.

Altogether, this is probably the second most significant prototype find in the last several years. There's a big jump in physical appearance and LCD type in a production window just a few weeks apart.

Critor beat me to the punch
Along with the TI-89s, there was also an interesting TI-86 prototype. It is a ViewScreen variant, which isn't very surprising, since TI does have a history of prototyping with ViewScreen units. Hardware-wise, the board revisions are earlier than the production models (9TILEOMB-30D instead of 9TILEOMB-30G and 9TILEOLB-30B instead of 9TILEOLB-30D). Perhaps the most interesting thing about it is the Atmel AT29C020 ROM which is socketed on the board (instead of being soldered directly to the board like production models). This allows it to be removed, reprogrammed and reinstalled without any soldering.


Left: socketed ROM chip, Right: regular soldered ROM chip

The ROM version (1.4001) is also unreleased...


Unsurprisingly, it is close to 1.4, but the fact that it is similar to 1.4 suggests that the calculator was used for many months to develop the OS because the hardware is identical (down to all the date codes on the chips) to the earliest known TI-86 which runs ROM 0.2026 but 1.4 wasn't released until 1998. It is not in great shape, but I guess that's to be expected of a calculator that's nearly 25 years old, particularly one that would have been opened up and closed frequently.
Here are the images, note the lack of a serial number on the back.



This is just speculation on my behalf, but its possible that the number drawn on the board in red is a form of serial number to keep track of the calculators, which would make this the 32nd TI-86. The only other similar calculator to date (this one from the Datamath Museum) also has a number drawn on the board (117).
This brings the grand total of discovered TI-86 prototypes to 3, 2 of which are mine
EDIT: This was found, new total: 2/4
I finally got everything set up to dump the ROMs, and I took the time to dump ROM 1.0 from the Display Sample I collected a few months ago.



I can confirm that like every other (more recent) ROM version that has been dumped, both 1.0 and 1.4001 also contain the strange "Willy DO BE DO BE DO" easter egg.

EDIT: After taking a closer look at 1.4001, it looks like it is larger than 1.4 due to the fact that it contains additional code to reflash the flash chip. If you look back at the two pictures of the socketed and not socketed chips, you'll notice that the socketed one is an AT29C020, which is a flash chip while the AT27C020 found in production models is an OTP-EPROM. This extra functionality can be accessed by pressing 2nd, MODE, ALPHA, F to put the calculator in a receive mode, waiting for an OS update to be sent via the linkport. Therefore 1.4001 is nearly identical to 1.4 if you ignore the additional code which handles receiving OS updates through the link port (and shuffle pages around of course). Here is the TI-Planet article regarding this rather significant find.

I received a TI-Nspire+ keypad and front cover yesterday.
For those who haven't heard of it, the TI-Nspire+ was an unreleased prototype of the TI-Nspire clickpad, developed as part of the Phoenix project

I asked the ebay seller if they happened to have the calculator itself (sometimes sellers will split calculator bits into multiple lots to maximize profits), but they didn't have any other relevant parts.
Unlike production keypads, the TI-Nspire+ keypads don't work in a regular TI-Nspire, so one would need a TI-Nspire+ in order to use it. There are only 2 known units, one is owned by Joerg from the Datamath museum and the other by comsmy (a collector/enthusiast in china). Comsmy's doesn't work and doesn't seem to be feasibly repairable. At the very least, none of the ribbon cables have been soldered to the boards which makes me think it might have been more of a display sample than a dev unit. Perhaps Joerg might be interested in working something out though.

Its possible to perform self-diagnostics without a TI-Nspire+ though, so I might give that a try if I get my hands on a regular TI-Nspire clickpad.



The board itself is held in place by a bunch of ultrasonic rivets which I'm not too keen on removing, even though the board number is on the other side. There's also no serial number or any information on the back, which is the same as Joerg's.
Along with the keypad, I also received the front cover, pictured here with the other TI-Nspire covers to show the color difference:


(Left to right: TI-Nspire ClickPad, TI-Nspire+, TI-Nspire CAS, TI-Nspire CAS TouchPad)

How does one just manage to get the keypad and not the calculator itself? Did they tell you if they already sold the calculator?
Nevertheless, you've got a growing list of awesome protos!

Nice collection of prototypes and photos .

I recently acquired 2 HP marketing samples, one is an HP 39G+ and the other is an HP 49G+. This is slightly off-brand since I'm not too familiar with HP calculators, but I figured these were clearly interesting enough to add to the collection



Right off the bat, we can see that the HP 39G+'s 2nd functions are green, which indicates that it is an early model since it was changed to orange shortly after production began (presumably because the contrast is particularly bad in green).
Both calculators lack the arrow at the top of the screen. Much like the TI-89 silkscreening, the old promotional images of both calculators didn't have the arrows at the top of the screen.


Production models with the arrows for reference



On the back, both are covered in stickers.
The HP 49G+ was released in August 2003 and the HP 39G+ in September 2003, so the dates seem to be about right for the final stages of prototyping/pre-release (July 2003). The HP 49G+ has a sticker stating that it is not fully working, but I didn't find any issues with it, however the HP 39G+ which doesn't have that sticker crashes when entering self-test.
We can also see that there are no serial numbers on either of them.
Here are the version screens for both of them containing the hardware versions, I'm not sure if these are earlier than the mass-produced revisions.



Finally, here is the self-test screen for the HP 49G+. Since the HP 39G+ crashes when entering self-test, I snapped a picture of the loading screen which contains the boot code version instead. I believe the earliest mass-produced HP 49G+'s contained boot 3.15.04, so this would be slightly earlier. It also says "NO SERIAL NUMBER" where the serial number would normally be, which looks mildly interesting

Let's take a look at the TI-Nspire CAS EZ-Spot P1R2-DVT1.1 prototype!
About a month ago, I got flooded with messages from Critor, Adriweb, TheLastMillennial and Ti64CLi regarding a prototype that had surfaced on r/TI_Calculators of all places (which I don't regularly patrol).
An engineering student named Rob (u/gooseloom) posted a series of images along with a request for some help getting his calculator out of diagnostics mode.
Of course, only early prototypes boot directly into the diags.
Rob was very cooperative and understanding of the fact that his calculator had some historical value and he seemed to agree that it would be preferable for it to find a home in the community in a collection. I don't know if he will read this post but if he does, I would like to express my gratitude to him for agreeing to sell the calculator.
Obviously, a few community members expressed interest in the calculator and after some deliberation with them and Rob, we put together a game plan that would satisfy the most people which involved me purchasing it for my collection and having it tour the world for everyone to take apart.
Now that the calculator has been received by Adriweb, we can take a closer look at it!



The pictures contained a number of noteworthy details:

• The symbol at the top left of the screen while Boot2 is executing, signifying that the OS is being validated with development keys.
  
• The complete lack of a serial number or any markings on the back, uncommon even for prototypes.
  
• The color of the case, an unreleased white and yellow EZ-Spot variant.
  
• The DVT1.1 Diags, previously only spotted once in this prototype from cnCalc.org in China.

The color of the case seems to be a CAS clickpad version of this non-CAS TI-Nspire EZ-Spot, but it looks nothing like the CAS EZ-Spot that was released which was completely yellow on the back.
It runs OS 1.1.4797 just like comsmy's DVT1.1. Unfortunately, the one from China was never dumped because it got destroyed in a failed upgrade attempt and was thought to be lost forever. This will therefore be a very lucky second chance at dumping it.
That being said, actually dumping it will be much easier said than done because it is such an early version that it doesn't have USB support implemented yet! This will mean having to dump it through the J04/JTAG connector using some custom hardware.
The only person with the required hardware and know-how is Critor, so the calculator will be going on a trip to France next December to be dumped.
Hardware-wise, it seems to be the same as comsmy's.



Note that it uses the newer ASIC processor rather than an OMAP. In fact, I believe it might be the earliest prototype found using the newer technology.
Also of course, there is the J04/JTAG connector which is populated and allows the SST NAND flash chip to be reflashed.
It seems to have been manufactured in December 2006, 1-2 months before the DVT1.2 and DVT2.0 prototypes.
One of the ribbon cables looks like it might have some surface-level damage but luckily, there are no issues with the LCD for now.

That's quite an awesome calculator! Will the ROM dump for this calculator be able to restore the one in China we thought was destroyed? Or is it permanently bricked?

The calculator wasn't bricked, the OS was deleted to install a newer version but because the 1.1.4797 Boot2 didn't have USB support, he was never able to install another OS. To answer your question, yes, if successfully dumped, it should be possible to install 1.1.4797 on any proto but not on production models.

I recently received two large boxes from Pieman7373 containing many calculators that I've purchased over the last couple years, including two TI-Nspire CAS TouchPad DVT1 prototypes. I'm very happy to have found these as touchpad prototypes seem to be among the rarest nspire prototypes.
This specific revision has been spotted once before from a user on cnCalc.org in 2014, although it was largely overshadowed by the much more interesting PROTOTYPE 014 which he showed off in the same post
The two units I've acquired are serial numbers 002 and 280.



There is a large customs sticker on the back of the 002 which contains general information about make and model.



This sticker is in Spanish because it was imported to Mexico. These calculators were sent to Hildebrando Services Inc. in Mexico which is a sub-contractor that works for TI to develop the apps, so these prototypes were used for software development (nothing too surprising for a DVT). One interesting thing to note about the import label is the Pedimento number (an ID given by the Mexican customs to each shipment), which is 9012083. This is interesting because it is the same as the one on the keypad that came with an EVT1 prototype that surfaced in 2015, meaning these calculators were in the same shipment as that EVT1. A similar sticker is also on one of the keypads.



Hardware-wise, both of them are identical to each other and also the same as the one that surfaced in china in 2014.



The LCD is N1/N3_LB_PCR2_FPC_2410, and the MB is N1_MB_NKB_4420.
The J04/JTAG pads have not been populated but are there, which suggests that it would likely be possible to establish a JTAG connection. On earlier prototypes (EVT), the JTAG connector was populated but it was towards the top of the MB, so around September 2009, it was moved towards the bottom of the board, probably because TI was doing this and also wanted access to the reset button

There's also no spot for the li-ion battery and the charging circuit is removed.

Software-wise, the S/N 002 contains OS 2.0.0.900, which as far as I know hasn't been spotted before and will need to be dumped. It also contains 10MB of files which seem to be various QA tests. I haven't had much time to look through them properly but I'm not expecting too much.



The S/N 280 contains no OS and both contain 2.00.DEVBUILD Diags.

I got a hold of a TI-Nspire CAS TP RCB-DVT1 prototype a couple days ago, which is pretty similar to the two DVT1 prototypes from the previous post.
It came to me untested without a keypad, but thankfully, it worked right out of the box after inserting one of my keypads from the collection and charging the battery a little bit. The top left screw was missing and the top right screw was a completely different screw from the normal TI screws. It was a phillips head screw which does make it easier to open, so its plausible that TI would internally only put 1 easily removable screw if they wanted to open and close it a lot, but I have no idea if that was always the case or if the screws got lost and replaced somewhere in the last 10 years.
This one was made 3 months after the earlier DVT1s, but followed a similar path. It also has the same style of shipping label stuck to the back, as well as an additional sticker attesting that it was in the hands of Hildebrando Services Inc. Unlike the earlier prototypes, this one, has a Li-Ion battery (like production versions). This didn't stop the customs people from slapping that big sticker on the back, making it harder to open!



The pedimento is different from the other ones, so this one was sent in a different shipment.
The serial number reads: "CAS RCB DVT1-NOT FOR SALE 188 P-1209", which is quite wordy. In fact, the font size is considerably smaller than it usually is.



That being said, we actually get a little bit more information than the earlier prototypes, notably, that it was manufactured by Inventec in Pudong, China, and that it is a CAS version. The fact that its a CAS version doesn't really mean much besides the color of the case, since it is the exact same hardware as this non-CAS prototype that was spotted a few years ago.
The LCD is TG2995-C-LB-2410, and the MB is PCB-TG2995D-MB-4420.



Software-wise, it has an in-between version that hasn't been spotted to date: OS 3.9.0.450
(The closest production OS that TI released is 3.9.0.461, which is just a handful of builds away so it will likely be very similar) It'll of course need to be dumped. I haven't had much success with Fron yet, hopefully this is just a mistake on my part and not a problem with the OS not being dumpable for some unknown reason.



The Diags also seem to be a new version (Iris Nspire Diag Menu 2.00.837 2009-12-1).

I recently got my hands on an interesting TI-84 Plus CE Display Sample. As the name suggests, these are generally made in very small numbers and are intended for display, for example, the calculators pictured in promotional materials are generally Display Samples and lack a serial number.

Here is an example of some Display Samples in a promotional picture for the charging stations that can be found in the guidebook:

Display Samples are sometimes fully functional calculators, such as the TI-86 I discussed a few posts ago, but in this case, there is a PCB but it isn't populated! I personally think that is even more interesting, although an unreleased build of the OS would have also been very exciting.



The one I found has a sticker on the back that identifies it as

The board is dated 1635 (35th week of 2016), which would have been around the time TI was producing revision B1 of the CE, so "B1.3 evaluation" would be in reference to the hardware and of course, "Sample for New color" suggests this would have been a planned but not released color variant.
You may also notice, the lack of a serial number and the mention of the phrase "NOT FOR SALE" just like the unreleased marketing sample colors from a while ago. Another interesting thing is that it seems to be signed by Matt T. Nicolisi, Senior Industrial Designer for Texas Instruments. He is from Ohio and the seller was also from Ohio so it is pretty safe to assume this was his sample. It is not the first time we see the names of TI employees on prototypes, presumably, this makes things easier internally, since there often aren't serial numbers attached to the protos

The color is definitely not something that was released and looks like a metallic blue. Here is a video from Adriweb showcasing the interesting color.



Finally, the board revision "SG93/F/T-10-1" is one that hadn't been spotted yet, however, I haven't seen the board revision of a rev B1, which I suspect might be what it is.

I have a couple protos that I haven't really talked about (besides in sax) so I guess its time to make a new post!
Recently, I got my hands on a very rare TI-82 Advanced Prototype!



The back reads "K-DVT-211 DVT NOT FOR SALE", indicating that it was made by Kinpo (Taiwan), it is in the DVT phase of development, and it is serial number 211. This is the same as the two other known TI-82 Advanced prototypes (Critor's sample and this one which was spotted being displayed at Orme 2.18 in Marseille in 2018). I suspect that there wasn't a whole lot of hardware development since the hardware is the same as the TI-84 Plus-T and they are both essentially the same as a TI-84 Plus (dbus replaced with an LED, just for you notipa ), so its possible that K-DVT is the only TI-82 Advanced prototype revision.



On the back, there is a sticker which says "Made in China", which is what initially prompted me to purchase it in the first place (The serial number was not visible at all in the blurry ebay listing)
This sticker is very telling for two reasons:

1. All known production models were made by Kinpo in the Philippines, while all known prototypes were made by Kinpo in Taiwan (which is definitely China and not an independent nation... )
   
2. On the MP TI-82 Advanced, this information is molded in the case, its not a sticker!

The hardware is the same as Critor's sample, which is the same as the mass produced pre-A revision (SG82F 10-1), however, both mine and Critors' have a bit of rework towards the top of the board around the USB port as evidenced by the flux residue. This is of course not the case for production models but the components are all the same so I'm assuming this was simply due to problems with early production.



The one spotted at Orme 2.18 ran OS 5.0.0.0028, which is the same as the mass production models. In fact, although the TI-82 Advanced can receive OS updates, that functionality has been pretty much unusable because TI only ever released 1 OS version! That being said, Critor's sample ran an earlier version (5.0.0.0014). That version has not been made publicly available because it is under NDA (When TI sends out samples like this, they generally make the guys from TiPlanet sign NDAs, which as far as I know, is the reason why the 5.0.0.0014 OS is not available for download on TiPlanet)
That's rather unfortunate since 5.0.0.0028 contains a pretty nasty bug with the special characters menu. When navigating this menu, sometimes the cursor doesn't get erased, lines go missing and random junk gets displayed on screen. Weirdly, this bug was not present on version 5.0.0.0014, so it must have been introduced quite late in the development...
In fact, that's one of the first things I checked when I received the calculator and I can confirm that 5.0.0.0027 also doesn't contain the bug, meaning that we could finally have an OS update (although it would be a slightly earlier version) which patches the bug. This is of course, assuming I can dump it, which is easier said than done!
Critor wrote a news article last month about my new calculator, focusing on this bug.

Regarding dumping a ROM image, its quite challenging because there aren't any polished tools to help out. With only 1 OS being released, nobody has really taken the time to create a nice dumper. That being said, I'm not starting from scratch because BrandonW and Critor have dumped a 5.0.0.0028 before to create the OS update file on TiPlanet and they have been very helpful although I still haven't managed to dump it. The 82 Advanced does not support assembly, but there exists an exploit that was used to get the calculator to dump itself. It is also not supported by TiLP, so BrandonW wrote a python script to receive the dump. It must also be dumped one page at a time by creating an individual backup file to dump each page (of which there are 35 ), presumably because it was initially only really meant to be used once. Thankfully, BrandonW also made a python script to generate the corrupted backup files.
So with these scripts in hand, I set out to dump it... Unfortunately, the dumper crashes my calc and doesn't dump I still haven't figured out why, but I plan to sit down and take a closer look eventually...

EDIT: I managed to dump it today with a corrupted backup file to install MirageOS. Its sprinkled into 64 seperate files right now (one for each flash page) but from here, its pretty straightforward to put together a ROM image and an OS update file.
EDIT2: The files have been mushed together into a ROM image and an OS update file was generate but it seems this OS fails validation when sent to a physical calculator. Assuming I didn't make any mistakes while dumping (I double checked), it appears that the signature from the proto is invalid. Perhaps they did like the nspire series and had a different set of keys for dev units and production units. Either way, since the 82A uses 2048 bit keys, we're out of luck in terms of signing it ourselves but the most important thing is that the ROM image is intact and saved even though it can't be distributed.

I usually try to wait until I receive the calculator in my own hands before making one of these posts, but this is one of the most interesting protos yet and I'm very happy to have snatched it.

First off, here's a small history of the quest for a TI-92 prototype.
TI-92 or any 68K prototypes seem exceedingly elusive, I don't know if this is because they didn't produce very many or if they were very good at keeping them from leaking. Until now, we only knew of 1 unit which is in Patrick Verstrepen's collection. Unfortunately, he had not provided any images of his proto, so all we really knew of it was the serial number and date code from the listing of his collection from 2012.
Over the years, I managed to find 1 very early TI-92 which strangely had an engraved serial number (01000489 I-0995).
Early Inventec TI-92 serial numbers were all stickers (for units made in Italy, they were engraved, but those came later and used a different serial number format).
This early unit contained ROM 1.0 compiled on September 19, 1995, which is different from the earliest known revision at the time, 1.0b1 compiled on September 13, 1995.
That unit is now in Adriweb's collection in France.
France is perhaps the best place to look for TI-92 prototypes because it seems like all the early stuff is from Europe, so I assume it was a TI-France project

Now on to the new developments:
From looking at promotional material from 1995, one main difference sticks out. The hand symbol in the top left corner had multiple iterations, only 1 of which (the first one) was commercialized.



From the listing on leboncoin.fr (a French second hand trading site like eBay), It was very clear that the hand symbol was the 3rd one without a wrist/cuff. EUREKA!
I began chatting with the seller and putting together a plan with Critor to retrieve this prototype.
In doing so, I learnt that not only was this a prototype, but it was a very early one. He confirmed that there were stickers on the back with the words "Engineering Sample not for sale" and "Prototype", as well as the serial and date code 01182 0595. Earlier than Patrick Verstrepen's! I also learnt that I was speaking with the original owner of the calculator. He was given the unit to test it and showcase it to teachers at conferences. He was hired as part of a team to write a book about chemistry and physics experiments assisted by the TI-92.



Luckily for us, the early TI-92 design had 2x 512k OTP EPROMs (1MB) in the expansion cartridge which contained the ROM, meaning that it could not have been updated over the years... At least, that's what I expected... When Critor received the calculator, he reported back and told me the ROM version was 1.12 (the most recent version from May 8, 1996!). Sooo it was updated ? Upon closer inspection, the prototype cartridge did not contain OTP-EPROM and in fact, contained FLASH ROM! Just like the TI-86 prototype from 1996, TI used flash for prototypes and ROM for production models, allowing them to reprogram the cartridge to update the ROM! In fact, the connector under the cartridge is an elastomeric "Zebra" connector as opposed to the female pin header. These connectors were quite popular in the 80s and 90s and were known to be unreliable over time, but it does make it easier to remove and reinstall the cartridge since it just sits on the pads. For this reason, I suspect that TI had an external programmer to reprogram the proto cartridges.



You may also have noticed that the 2 Intel flash chips are 8MB (1024x8) chips, for a total of 2MB of memory. Twice as much as the production cartridges with OTP-EPROM!
Thankfully, the prototype also had a ROM chip soldered on the MB like later revisions of the TI-92 and that one was not flash. Indeed, it contained the original ROM version from when the unit was produced, 0.5d23 compiled on January 16th 1995, a full 8 months before the earliest known production ROM (1.0b1 from September 13th 1995)!



Evidently, the ROM is very different from production models. The about screen gives a lot more information and options, notably the amount of available RAM, the state of the stack and the option to turn APD off.
In the self test menu, there is also additional options to "PEEK" and "POKE" memory addresses (to read and write to individual addresses).

On the inside, the hardware is similar to production models with a few notable distinctions.

• The RAM is the same but in a DIP SOP package instead of its usual TSOP.
  
• Obviously the layout of the board is different
  
• The communications circuit for the dbus seems to be the old design used in the TI-82/TI-80, although it should be functionally the same
  
• There are 2 pads labelled VCC and GND. I'm not sure why they would want to measure the power rails? Maybe this helped them to diagnose hardware issues?
  
• The mask ROM soldered on the MB is a generic 1MB Sharp CMOS
  
• The 3 column drivers are a slightly earlier version than the one that made it to production (T6A39 instead of T6A39A)

Now on to dumping... This is easier said than done. Like a lot of TI calculators, the TI-92 doesn't support native code. There exists a shell (Fargo) which allows us to run machine code, but it has been tailormade for each ROM version and is thus incompatible with this early ROM. The last update of Fargo was in 1998, 23 years ago and the person who developed it (David Ellsworth) has since left the community long ago...
However, I managed to track him down and have begun discussing this with him. He seems very willing to give a helping hand in preserving this unique find
He informed me that time has not been kind to his calculators. One of his TI-92s got lost in 1999 and his other TI-92 no longer works even though it was kept in a drawer

Along with this unit, the seller also had another TI-92 prototype without a viewscreen connector which he said was slightly newer. That one was purchased by Critor for his own collection and has yet to be received. It will surely also contain a treasure trove of goodies . Hopefully that one also has an OTP-EPROM chip that could not have been updated.

Special thanks to Critor for receiving the calc, taking pictures/documenting his findings and hopefully helping to dump it.

EDIT: Critor and Lionel managed to dump 0.5d23 through the external module (1.12) and have provided me with a copy. The other TI-92 purchased by Critor contains 0.6a19, however, that version is on the external flash module so it cannot be dumped using the same method.

The last hand symbol:



TI were 'gotcha!' pioneers! .

Great job to critor and Lionel getting the new ROM dumped. Interesting how there haven't been many TI-92 protos found- I would've thought that, it being a completely new form factor for TI calcs, the development process would be long and involve many protos (like how there are so many Nspire protos). Anyways, it's pretty awesome that David Ellsworth was able to help you out in this.

Getting the 0.5d23 internal ROM dumped was achieved through a couple modifications in the Fargo dumper:
* hard-coding ROM_base and ROM_size respectively to 0x200000 and 0x400000, to dump both the internal and the external ROM / Flash in one fell swoop;
* adding 5 nops for the dumper binary's size not to change.
Needless to say, the latter shouldn't have been necessary, and I need to investigate when I can find some time

Haha, if you're really observant, you might have noticed its actually the icon that ended up being used in the voyage 200 a few years later



And the other unused icon ended up on all the nspires.



I actually had this same reflection a while ago. I would expect there to be more TI-92 protos than other calcs simply due to the fact that it was the first 68k (completely new hardware for TI) and the first CAS, as well as a completely new OS, so the software was all from scratch as well.
Looking at the 2 protos we now have (0595 and 0695), which are a good 7-8 months before release, I'm actually pretty surprised by how similar they are to the final product. They were almost ready for release at that point, so TI must have been working on the TI-92 well into 1994, if not 1993.

In the case of the nspires, there were lots because they were sent to schools for pilot tests, and then TI never recovered them. On top of that, it seems like some protos were sent to china to be destroyed by a third party and some of those have resurfaced as well. TI also sent some protos down to HITSS in Mexico for the development of apps and some sample software assignments to be used by teachers. Basically, it looks like TI spent almost 2 years shedding protos left and right not really caring where they ended up

I actually think that TI did pilot tests in classrooms with the TI-92, but its unclear whether those were "protos" or not and if they were protos, it would seem like TI recovered them at the end. Either that, or the pilot tests were really small scale with just one or a few classrooms and we just haven't been able to spot any yet.