I think it is the blue screen of death. Putting DrawInv
Shade(63)
DispGraph
Repeat getKey
End
Shade(47)before the suspect code lets you see the difference
I tested it on my calc lol (good decision? It hasn't exploded yet...)

So weird... I'm getting my calc an viewing the disassembly in calcsys to see how this happened (I still refuse to execute it)

Well, it doesn't happen in 0.2.3 (which I have, I'm waiting for 0.3.0 to upgrade), so I'm afraid I'm of no further use w/o the program generated by the most recent version

Okay, I did my research.  This is what appears to be happening.  I believe that there is a very short voltage spike between changing contrast from a very low value to a very high value and vise versa.  You don't see the screen turn blue normally becasue its so fast that you can't even see it.  However, if you alternate the screen very rapidly, the voltage spike appears often enough that it becomes very noticeable.  So this is a faulty hardware problem and there is nothing I can do about it.  I'll just have to trust that you're all being safe about using it.

Here were some clues that led me to my hypothesis:

• You can't get the calculator to stay in a blue state unless the contrast is constantly changing
• The degree of blueness is continuous.  There is not a single shade of blue.
• The degree of blueness is directly proportional to the difference of the values you alternate between
• The degree of blueness is inversely proportional to the amount of pause you have

All of these suggest that the calculator is NOT in test mode.  So this blue is actually less voltage on average than test mode, but that still doesn't mean its remotely safe.  It probably won't fry your calculator right away like the real test mode, but it can certainly damage it over a longer period.  I absolutely do not recommend exploiting this effect.

lol i thought it was supposed to be blue!
i really did.
right when i started to learn axe i made a prog the displayed "hello world"
I had it go from 0 to the max contrast and back again. over and over again.
i don't think i need to mention it turned blue.
 thought that was supposed to do that.

Wow, that's pretty odd.  Nice find Quigibo.

Okay, I did my research.  This is what appears to be happening.  I believe that there is a very short voltage spike between changing contrast from a very low value to a very high value and vise versa.  You don't see the screen turn blue normally becasue its so fast that you can't even see it.  However, if you alternate the screen very rapidly, the voltage spike appears often enough that it becomes very noticeable.  So this is a faulty hardware problem and there is nothing I can do about it.  I'll just have to trust that you're all being safe about using it.

Here were some clues that led me to my hypothesis:

• You can't get the calculator to stay in a blue state unless the contrast is constantly changing
• The degree of blueness is continuous.  There is not a single shade of blue.
• The degree of blueness is directly proportional to the difference of the values you alternate between
• The degree of blueness is inversely proportional to the amount of pause you have

All of these suggest that the calculator is NOT in test mode.  So this blue is actually less voltage on average than test mode, but that still doesn't mean its remotely safe.  It probably won't fry your calculator right away like the real test mode, but it can certainly damage it over a longer period.  I absolutely do not recommend exploiting this effect.

Wow exactly what I thought (well, I did not know what caused it but I had it happen on my 83+SE). When shutting down the calc from Mirage on 15 MHz calcs, notice how sometimes the screen quickly flashes to black then turns off. Same happens when reducing contrast to a low level quickly. Some xLIB games uses such method of alternating contrast quickly to create the blue effect. The way they were used is not dangerous, because it's not as bad as test mode, but if you leave the calc this way over a very long period, it could be.

Btw that trick doesn't work on the regular 83+ or emulators. It only works on real 83+SE, 84+ or 84+SE hardware.

Nice find Quigibo! I've been wondering since 2002 why my SE flashed quickly to black when turning it off most of the time