Omnimaga
Calculator Community => Other Calculators => Topic started by: CVSoft on January 26, 2012, 09:14:17 pm
-
Browsing around eBay, I noticed that some TI-81s have a screen that is off-white and have bluish-gray pixels, while others have the standard STN screen like a TI-82. Did TI change the screen type?
http://mycalcdb.free.fr/main.php?l=0&id=1842
vs
http://www.partlancer.com/pics/TI-81-Graphing-Calculator-WORKS-FOR-SCHOOL-LOOK.JPG.jpg
-
I'm not sure. Ti does change stuff sometimes (ti 82s and ti 83s have different screens on different models). Sometimess screens just look different due to crummy pictures. You shold check data math and see if they have any info on it.
-
My understanding from talking with people like Ben Moody, Randy Compton, and Michael Vincent is that some TI-81 units did indeed have a different LCD. I think some of the earliest ones had the high-contrast bluish ones like the 82 and 85, but most of them (like my ROM 2.0V one) had the grayish, poor-contrast version with only ten contrast settings instead of 32. Not sure why they would switch to a worse version unless it was due to cost.
Interestingly, the interface with the LCD changed on some models, too. Apparently early TI-81s had a memory-mapped display like the TI-85 and 86, while the later ones (2.0V and above?) reverted to an 82-style display driver and hacked in an interrupt routine to periodically copy the entire display to the driver. This often results in an odd, slow, flickery effect when running programs that rapidly clear and display text on the screen on these units.
-
Actually the first models had the light gray (hard to see) ones, since I got one of the first models (without the button battery slot). I never got to see a newer one, though. As for memory mapped-ness, I wonder if this is why the Disp command is faster on my TI-81 than the other models?
-
Perhaps they switched back and forth once or twice, since yours (1.1K or something, IIRC?) and mine (2.0V) have gray LCDs, but I think Randy said his 1.8K model had the blue one.
As for Disp speed, the models with memory-mapped displays would certainly appear faster (or at least, less choppy). I'm not sure if this alone could account for actual speed in terms of lines printed per second, unless the slow copy-to-driver interrupt routine consumes enough time to noticeably slow down everything else (which it may or may not, I don't know).
-
I wonder what LCD does the ROM 1.0 calcs got? If I remember, though, on Datamath for a while the 2nd model listed seemed to have a blue LCD, but it might have been due to the camera lightning.
-
I found clearer pics of TI-81 screens on Datamath via web archive. Those show a change in screen starting in ~1995, consistent with below. However, there were only two at the time.
Based on comparison, I noticed the following trend, listed in order of appearance on the current Datamath page:
The ES cannot be determined, appears blue
The second appears to have a blue screen
The third has a blue screen
The fourth has a gray screen
The fifth has a gray screen
Seems they reduced quality then. For cost reasons they probably put in a lower-quality screen in the very first ones to see how well it performed in the market (?). That's just my guess.
eBay also makes a good photo repository IMO.
-
Was the third with ROM 1.1K? Because mine has 1.1K from 1991 and has a gray LCD.
As for Ebay I tend to not take photos for granted, though, because in many occasions I found people using genetic photos of an item instead of taking a picture, and as a result, the calculator looked slightly different from the pic.
-
Looking closer, it seems the gray screens are more pixely than the blue screens. That means only the third one used a blue screen, which seems correct. I should look before I post :P .
-
I had an old 1.8K TI-81 with the blue screen.
-
I have a TI-81 around my house somewhere. It was used maybe a little to heavily until it's unfortunate demise in the -45˚C(-50˚F) weather in Alaska. It had bluish pixels though.
-
Looking around on Datamath and eBay, they all appear to be first-generation TI-81s manufactured in the second half of 1992, which is immediately before the release of the TI-82. I'm not sure if it had to do with a limited supply of the screens or just profit-reaping.
-
(hopefully acceptable necrodoublepost) After browsing through several hundred eBay listings, they were all manufactured between mid 1992 and early 1993, with hardware B. It also includes ViewScreen models, but I am unsure about the attached screen. I also noticed that the first-generation TI-81s without backup batteries are quite common.
-
Yeah I have the second wave of 1st gen calc with OS 1.1K or something, which also lacked the battery. IIRC the early 81's have a memory-mapped screen and display is much faster than on the TI-84 Plus in some cases.
-
TI did switch the hardware around a lot on the 81. I have a later TI-81 (2.0V, hardware revision F) and it doesn't have the memory-mapped screen. I've taken pictures of partial characters on the screen, mid-refresh.
-
Good detective work there. :) Also, the backup battery missing in some models is weird. By design it's clear that there was intended to be space for one.
-
Perhaps they had problems with making the backup battery terminals fit inside the calculator, or that the backup battery was causing problems with the RAM. Either way, they intended to have one (http://datamath.org/Graphing/TI-81_I0991.htm) but it didn't happen.
-
Yea, I saw that page too. I was looking at some stuff the other day and decided to see if data math had any info. Gotta love datamath. :D
-
Yeah my 81 has a round space where would be a backup battery, but none can be inserted. By the way how long are those batteries supposed to last? In NES games some of my batteries have lasted for 25+ years and still keeps my saves fine, while some other NES or even SNES games had dead batteries after only 3 years. Also TI says to replace the battery after 3 years, yet mines worked fine for nearly a decade in some cases.
-
All of my calcs are still on the original backup batteries, the oldest being my 1994 TI-85 (which is 19 years this month :D )
Datamath has a lot of goodies that aren't well linked, for some reason.
-
It's possible that the backup battery has been changed at some point before you had the calculator. Unless it's a family heirloom or something. :P
-
At least on the 85 it ws used for a year and kept in a drawer for a little over a decade before I got it. I doubt it was ever changed.
-
I don't think I've ever changed the backup batteries on any of my calcs. I don't use my oldest ones anymore, and I don't even remember if they still remember the memory contents. I think if the main batteries are out long enough some of them might do a RAM clear, but they seem to be able to retain it for short periods.
I also have some Game Boy carts approaching 15–20+ years and haven't had any dead saves yet. :) Never any problems with NES/SNES ones back in the day, either, though Nintendo said they would last 5 years.
-
( I lost my 249 PKMNS with a depleted battery... Poor Gold version)
Have batteries existed from the beggining?
-
Pokemon Gold and Silver last much shorter than every other game in average because the games have an internal clock feature that runs 24/7, draining even more power. The day/night clock feature was removed in 3rd generation games for that reason.
-
Pokemon Gold and Silver last much shorter than every other game in average because the games have an internal clock feature that runs 24/7, draining even more power. The day/night clock feature was removed in 3rd generation games for that reason.
There was a RTC in Ruby/Sapphire. They lasted ONE year.
-
Really? Wikipedia said otherwise the last time I checked (and cited dead batteries as reason why) ???
-
There was a clock too. But there aren't any day/night difference. Only elapsed time for berry growing.
-
Yeah I read now on Wikipedia that day and night is definitively gone. I guess that still leaving a clock in for other purposes still drains the battery fast enough, though. Also the battery problems with 2nd and 3rd gen Pokémon games brings up another question that is more related to calcs: If a TI-84 Plus is left with the 4 AAA batteries removed for a long time, will the small button battery drain faster than older calcs due to the clock?
-
Well, a calc that has AAA batteries installed isn't drawing very much current from the battery, hence hence the long battery lives. Someone with the proper tools should test this quantitatively.
-
Just make sure to remove the AAA batteries when not using the calc for a long while (especially years), else they slowly die then start leaking, which can cause permanent damage to circuits. In fact, I sometimes had leaking batteries after only half a year of non-use. It's worse in newer calcs it seems.
-
Hopefully this isn't too necrotic, but it's definitely relevant.
I picked up a TI-81, S/N 1210793 and an unreadable-from-pictures date code. It has the blue-on-green screen, and takes a backup battery. Once it arrives I will do some analysis of it. I have noted that the very early models (such as the pre-1991 models without a backup battery) with no letter after the date code have the gray-on-white screen seen on the later models. Using the blue-on-green screens must have been a short phase in the TI-81 life cycle.
-
Sounds very interesting, thanks for sharing. :)
-
I didn't forget, I was just busy >_>
1210793 I-1292 B:
(http://i.imgur.com/poVWIj1l.jpg) (http://i.imgur.com/poVWIj1.jpg)
17050114 I-0594 F:
(http://i.imgur.com/ZTsPKe1l.jpg) (http://i.imgur.com/ZTsPKe1.jpg)
A bunch of pictures of various calculator screens, contained in 40 MB of wonderful PNG quality, can be found here (https://www.dropbox.com/s/hcxcht6ymeflu1w/calcscreens.zip?dl=1). Included are these two TI-81s, two TI-82s (one with old display hardware (http://tiplanet.org/forum/viewtopic.php?p=180795#p180795), the other with new display hardware), a first-generation TI-83, first-generation TI-85, and my Nam Tai-produced TI-86.
Also of note is that there are 40 contrast steps on the HW-'B' TI-81, but just 10 on the HW-'F' TI-81.
-
[ultra-necrobump]
0454913 I-0493B
(http://i.imgur.com/nvPibJI.jpg)
So, I guess there are some exceptions for calculators produced in the week or so when the TI-81 transitioned to the V2.00 hardware and new housing.