TDS Survey Problem


I have a 48GX with TDS survey cards installed. I took out batteries but it was about an hour before new batteries were installed. I entered alpha alpha TDS48 to get back into the TDS software but I get a message "Insert Install Card'. I DO NOT want to lose data on the memory card as I have no way of doing a job over.


You presumably have two TDS cards: the ROM card (COGO and data collecting software) and the RAM card (where your data points are stored). If the RAM card's cell battery is still in good shape, then you should be ok data-wise. Just make sure you DO NOT remove the battery in the RAM card. If, on the other hand, you have one of these "no-battery RAM cards," then it is quite possible you are out of luck. These cards have a built-in battery that recharge themselves using the main three AAA batteries as their power source. It is often the case that these cards do not hold their data for very long when removed from the HP48GX, or when inserted into an HP48GX without main batteries. (I know for sure that SMI's newer RAM cards are like this; I'm not too keen on the newer TDS RAM cards.)

Assuming your RAM card does have a removable cell battery (DON'T REMOVE IT), then your RAM card data should be accessible, still. Here's on possible explanation for what happened.

The calculator's main memory obtains power from the three AAA batteries. If no batteries are present, there is an electrolytic capacitor within which will give users ample time to replace the main batteries (but I am sure it is does not provide an hour's worth of charge). When you removed the batteries, the built-in memory was probably cleared after the electrolytic capacitor completely disharged. Thus, your personal TDS survey settings likely got deleted, and now you need reinstallation. According to TDS, reinstallation requires that the ROM card be placed in card slot two. Refer to:

With the ROM card in slot one, and no initialized configurations, the ROM card produces the error regarding reinstallation.

So to fix the problem (again, this assumes your RAM card's battery is fine), you should be able to:

1. Turn the HP48GX off and remove the RAM card from card slot two.

2. Place the ROM card in card slot two. Turn on the HP48GX. Type in TDS48 to reinstall the default settings and reboot the calculator. This will initialize the calculator. Once this is done, turn the HP48GX off again.

3. With the calculator off, remove the ROM card and reinsert it into card slot one this time.

4. Place the RAM card into card slot two. If you would like to be super careful, you may also wish to write-protect your RAM card to prevent anything from writing to it (in particular, you do not want the survey software to reinitialize your RAM card).

5. Turn the HP48GX back on, and everything _should_ be back to normal. Back up your data from your RAM card as soon as you can.

6. If you would like to return the RAM card back to writeable mode, make sure to do so after backing up, and after you have turned the HP48GX off.

Good luck! Tell us how it goes!


Edited: 18 Apr 2006, 1:34 p.m.


Just another addendum: Never remove the batteries unless you are ready to replace them with another fresh set. Even though your HP48GX may report low batteries, the batteries themselves are capable of retaining the contents of user memory so long as that's all the batteries have to do. One normally has about a few minutes to change the batteries so long as the calculator remains in the OFF state.


Another note: A RAM card is powered from its own lithium coin cell when it's removed or the 48 is turned off, and it's powered by the 48's three AAA cells when it's inserted and the calculator is turned on.

To change the lithium cell in the card without losing the card's contents, do it with the card inserted and the 48 turned on.



I hope he was able to recover his data.


This was a problem with the tds 48 programs from the first versions on down to at least V4.1. I know Vs 1.4, 1.8, 3.1 and 3.2 had it too. TDS just never cared enough to fix it. At one time you could send the card to Corvallis and they would extract your data and send you back your card and a disk, for free. Don't ask me how this could have been easier than fixing the bug. Maybe they still do it or can refer you to someone who still can.
BTW: TDS 41 (the former surveyors co-op module) did not have this problem. It was written by surveyors who program, not programmers who pretend. Good luck.


What follows is pure speculation:

I suspect that TDS likely uses a 256K chip or some equivalent ROM setup. As they require placing the ROM card into slot two, it seems plausible that the upper memory bank contains all the default configuration files which get copied into user memory among other data that is not required during runtime. The added benefit of doing so is that it prevents ROM copiers from duplicating the contents without some software hacking. Once the config files are copied over into user space, the ROM card is then placed into card slot one, where the config routine likely checks various parameters that are obtained from the config files.

This seems to also be the case for the SMI's software (Elite series). Only they do not require installation via card slot two. It's my understanding that only 128K of memory can be accessed at any given time, and that card slot one can only see 128K. However, based on the hardware, it would seem possible that through software bank-switching, one could still access a different bank of memory from card slot one. I vaguely recall reading that TDS's HP48SX software does this; however I cannot confirm this without researching comp.sys.hp48 (and I feel too lazy at the moment to do so =) And since card slot one in an HP48GX is physically identical to either card slot of an HP48SX, it is within reason to assume that the same techniques have been carried over into ROM cards.

Edited: 18 Apr 2006, 11:31 p.m.

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