Intellivision Carts - hot swappable?

[BigO]

I was messing with an Intellivision 2 I got recently.

 

While cleaning cartridges and fighting with the stupid power switch trying to figure out why the games weren't working, I noticed that if I plugged a cartridge in with the console powered up, it would read the cartridge and start the game.

 

Is that designed-in behavior? It works pretty consistently.

Does this machine have an OS on board that sits there and watches for a cartridge to be plugged in? I expected it to be more like the 2600.

Does it detect the insertion of a cartridge and reboot itself?

Am I going to create a tear in the fabric of space and time if I do this?

[Prodos8]

To my knowledge that's not a good idea on the Inty.

 

I've heard/read the the Atari 5200 is designed to do it though. It triggers a reset or something when you swap a cart w/power on. I don't do that with my system just to be on the safe side.

[BigO]

It was an accident the first time. I then had to see if I saw what I thought I saw.

 

I wouldn't do it as a standard practice. But, I am tempted to rig a shut-off-immediately switch on the console. Is five seconds really so long to wait? It seems to be. I think the switch needs a good cleaning as it didn't seem to work consistently to shut down the console.

 

Those fire buttons...ouchie. I probably won't play it much with those controllers. There should be a better controller...

 

Thanks for the info, Prodos8. I wasn't aware of that feature on the 5200. I'll have to check further into both.

 

Does the INTV have a bios sorta thingamajiggie in it? If not, it almost has to be triggering some sort of reset when it somehow detects the cartridge in order to implement the behavior I saw. I guess my next move toward understanding is to find a good schematic for the INTV2.

Edited January 19, 2008 by BigO

[Tempest]

Does the INTV have a bios sorta thingamajiggie in it?

 

Yes, as does the 5200. Thats why you get a "splash screen" when you start up the system.

 

Tempest

[BigO]

Does the INTV have a bios sorta thingamajiggie in it?

 

Yes, as does the 5200. Thats why you get a "splash screen" when you start up the system.

 

Tempest

 

I don't get a splash screen when I start it without a cartridge though. Is the splash not just part of the program? (I dunno nuthin' about programmin' no 5200 and even less about programming the INTV.) How does the OS contribute to or utilize the ability to display a splash? Is there some program or hardware initialization going on during that time? Inquiring minds and all that...

[Tempest]

Does the INTV have a bios sorta thingamajiggie in it?

 

Yes, as does the 5200. Thats why you get a "splash screen" when you start up the system.

 

Tempest

 

I don't get a splash screen when I start it without a cartridge though. Is the splash not just part of the program? (I dunno nuthin' about programmin' no 5200 and even less about programming the INTV.) How does the OS contribute to or utilize the ability to display a splash? Is there some program or hardware initialization going on during that time? Inquiring minds and all that...

 

I believe the screen comes up as part of the initialization routine of the cartridge. The cartridge makes some call to the OS and gives it some information to put in the start up screen (like the game name, last two digits of the copyright year, etc.). This is the same kind of thing that the Colecovision does.

 

Tempest

[BigO]

Thank you.

[cschell]

Yes, there is a BIOS in the Inty, it's referred to as the EXEC. It contains various stock routines that games can use, one of which is the standard title screen template. If the correct bits are set in the game header it's possible to skip the standard startup screen and display whatever you want. It's also completely possible to write a game that uses no part of the EXEC. Most of the modern Inty homebrews do this. Partly because the specs for the EXEC have never been released and there are some IP issues, but mostly because the EXEC is largely responsible for the sluggishness associated with Inty games and you can build a more responsive 60Hz refresh game if you don't use it. (See the Space Patrol game just released as an example.)

 

The console will not work without a cartridge plugged in because the bus control lines are actually looped out through the cartridge and back into the console. If the cartridge isn't plugged in then most of the electronics in the Intellivision will never see the critical bus signals required to make them operate. Probably done this way with the intention that an add-on peripheral could intercept the lines and do more than just pass them through to effectively hi-jack more control of the console, but it was never done to my knowledge.

 

As for why you can plug carts in and reset the console, that's because the reset line on the Inty is connected to the cartridge port in such a way that plugging in a standard cartridge will reset the console. Unlike the 5200 I'm not aware of this ever being announced as the way to do things on an Intellivision, which makes me suspect this could be bad for either the cart or the console. Most modern hot-swappable devices ensure that power and ground connect before any I/O pins so that the hot-swapped part is in a known state before I/O is active. That's not true on Intellivision carts.

[BigO]

Very informative. Thanks for sharing your expert knowledge. I'm getting more intellivisient by the hour.

 

That's a very interesting thing to know about the control lines being looped out. That would seem to offer potential for upgrades and interfaces of various sorts with the busses available to be fully under the control of a peripheral. The nosedive taken by the industry would have killed of any plans anyone had cooked up to exploit that feature, but I'm surprised that no such plans have ever been turned up. I suppose the thing never got far enough along in its lifecycle to need to be upgraded.

[BigO]

A slight left turn, but on the subject of INTV hardware. Were there any 3rd party or upgraded controllers produced?

All I could find in the few places I looked were things that attached to the controller disk of the standard controller.

 

I haven't played it enough to get frustrated with the disk, but one needn't even play a game to feel the pain of the INTV2 stock controller fire buttons.

Edited January 19, 2008 by BigO

[B.U.Terriers]

A slight left turn, but on the subject of INTV hardware. Were there any 3rd party or upgraded controllers produced?

All I could find in the few places I looked were things that attached to the controller disk of the standard controller.

 

I haven't played it enough to get frustrated with the disk, but one needn't even play a game to feel the pain of the INTV2 stock controller fire buttons.

 

I've seen 3rd party INTV II controllers on eBay. The only way to use an INTV II in my opinion!

[B.U.Terriers]

A slight left turn, but on the subject of INTV hardware. Were there any 3rd party or upgraded controllers produced?

All I could find in the few places I looked were things that attached to the controller disk of the standard controller.

 

I haven't played it enough to get frustrated with the disk, but one needn't even play a game to feel the pain of the INTV2 stock controller fire buttons.

 

I've seen 3rd party INTV II controllers on eBay. The only way to use an INTV II in my opinion!

[Phantom]

The best thing you can buy for any INTV controllers are a pair of these if you can find them.

They work best and secure well so it feels like a stock Joystick IMO. Cheers