What Happens When You Turn On The 2600 w/o a Cart?

[Joe Stella]

Does anyone have more detail on what happens when you turn on a 2600 without a cart?

 

I imagine it jumps to the memory location it expects to find the cart, and crashes. But why is the result always different, and is it true that this can damage the machine?

 

On a related note, we discovered a long time ago that by toggleing the power or reset switches, we could sometimes play a "variant" on a game (I remember Space Invaders could be played without sprite collision, or something similar to that) or introduce graphic glitches. Why is that?

 

Just curious.

[Nukey Shay]

I don't really know about the cart thing. I imagine it's because there is no kernal to do the display, so the hardware is simply grabbing whatever value that is in the Ram locations and throwing them up over and over (i.e. bars and steady tones).

As far as the frying is concerned, I think it was mentioned before that the program skips ahead to a random location without initializing the Ram...leaving pointers and other things out of whack.

I don't think that either can actually hurt the hardware, though frying can wear out the switch or maybe shorten the lifespan of the circuits being spiked repeatedly (?)

[Vigo]

When the VCS is turned on without a cart, the 6507 CPU constantly reads #$FF´s while accessing ROM space running, and the RAM & TIA hardware registers have random values causing these interesting display images, since the TIA itself has no /RESET line (unlike other graphics chips) However, this wont harm your VCS, since you do not do any electrical harm to the hardware.

[Csonicgo]

sometimes a grey line shows up, it's diagonal.... what is this?

[EricBall]

sometimes a grey line shows up, it's diagonal.... what is this?

 

This is probably more to do with your TV. Since the 2600 CPU is trying to execute code which doesn't exist it isn't causing the TIA to generate VSYNC or a valid frame.