Intellivision II, why incompatible?

[CrazyBoss]

Hi.

 

Maybe it have been up before, but why did they maybe Intellivision II, incompatible with some games?

 

Why make it incompatible ? cause they wanted to lock out 3rd party games?

 

In commercials they actually said "It play all your games the old intellivision plays"

 

Sony Playstation, had many versions too, but the "Ps One" still plays games which was programmed for the 1st version.

 

I know its about some changes in the Exec, but I dont think it was a mistake, I am quite sure they had a reason to block those games ?

 

 

 

[Bamse]

I believe they changed the Exec to look for Mattel on the title screen which obviously third part publishers wouldn't have. This was done to stop third party publishers releasing games for the intellivision.

 

I did wonder why Imagic games still worked taking that into account but also wondered if this was because Imagic games don't actually have a title screen in the first place.

Edited April 5, 2019 by Bamse

[mr_me]

Yes, it was designed to make third party games incompatible on purpose. From someone that worked at Mattel Electronics at the time: https://web.archive.org/web/20180723191009/http://www.intellivisionlives.com/bluesky/hardware/intelli2_tech.html

 

In those days Mattel and Atari made a lot of money from selling cartridges but nothing from third party cartridges. They saw them as competition. Atari sued Activision however, forcing them to pay license fees but they couldn't stop others.

 

The intellivision ii exec has a couple of checks before it blocks launching the cartridge, one of which is the copyright year used by the default titlescreen. It wasn't hard for programmers to figure out and defeat the lockout. Here's a technical explanation. http://atariage.com/forums/topic/224032-intellivision-ii-coleco-compatibly-mod-explanation/

Edited April 5, 2019 by mr_me

[mr_me]

 

I think coleco was the first outside company with intellivision games before intellivision ii was out. Not sure of the exact release dates but looks like Activision and Imagic had a couple of cartridges out before the intellivision ii. Unlike coleco, they had some former Mattel programmers, and may have known the secret.

 

The plimpton commercial says intellivision ii "plays the same great games", not necessarily all of them.

Edited April 5, 2019 by mr_me

[R_Leo_1]

Is there any way to restore compatibility for the system?

[CharonPDX]

Is there any way to restore compatibility for the system?

 

If you use an LTO Flash, it can patch game ROMs on-the-fly to make them compatible with the Inty II. But as far as I know, there is no way to make the Inty II itself "fixed." I suppose if you swapped out the ROM chips for ones from another Intellivision model that doesn't have the issue...

[mr_me]

The regular intellivision exec is on two 2K chips where the intellivision ii exec is on a single chip. You could swap the intellivision ii exec chip with the 40-pin r03-9502 but you'd have to find a way to hack-in the 28-pin r03-9504. I think that would work. But then you'd lose the benefit of locking out coleco donkey kong.

Edited April 5, 2019 by mr_me

[intvnut]

The lockout was apparently worked on in secret, as indicated in the archive links above. And in one of the other links, you can see my dissection on how it works. The description at the archive link is a little scrambled: There's two separate checks, and one of them needs to succeed: Date range and "magic bit." If the date is in-range or the magic bit is set, the game will run. The magic bit is bit 6 of the "keyclicks word" in the cartridge header.

 

FWIW, LTO Flash! does offer a workaround, although it doesn't actually patch the ROM. It does some other magic. You can see this for yourself if you make a purposefully-incompatible ROM that checksums its own contents. The checksum remains correct.

 

There isn't a good way to modify the console itself to disable the lockout. As others point out, there wasn't a single-chip version of the EXEC other than the Intellivision II and the INTV88 (TutorVision/TutorPro). The latter uses an RO9580, which lacks the bus decode circuitry for the PSG and scratch RAM, and I think also does not respond to IAB.

 

It could be possible to build a daughtercard to replace the EXEC chip with a modified JLP board. I'm not sure it's worth it.

[intvnut]

Also, the archive description of why Word Fun doesn't work is also slightly inaccurate. Word Fun does use the built-in title screen code for its title screen, and in fact, that title screen passes the Inty II lockout check.

 

The issue is that Word Fun was actually written as 3 separate EXEC-based programs, plus a fourth "launcher." It uses a little-known and little-used EXEC feature to string these four sub-programs together, and that's what trips it up.

 

The cartridge header (known as Universal Data Block/UDB in Your Friend, The EXEC) contains pointers used by the EXEC for loading graphics, establishing timed tasks, and so on. You can change where the UDB lives by writing its address to location $2F0 and re-initializing the EXEC.

 

The 3 separate sub-games in Word Fun each have their own UDB. When you pick one of the games, the launcher rewrites the UDB pointer and reinitializes the EXEC, so that the EXEC can load the pictures and such associated with the sub-game.

 

Because those second-level UDBs don't have title screens associated with them, they don't set copyright years or anything else. When the launcher asks the EXEC to re-initialize, it performs the lockout check again on this new UDB, and freezes at that point.

[+Lathe26]

Also, the archive description of why Word Fun doesn't work is also slightly inaccurate. Word Fun does use the built-in title screen code for its title screen, and in fact, that title screen passes the Inty II lockout check.

 

The issue is that Word Fun was actually written as 3 separate EXEC-based programs, plus a fourth "launcher." It uses a little-known and little-used EXEC feature to string these four sub-programs together, and that's what trips it up.

 

The cartridge header (known as Universal Data Block/UDB in Your Friend, The EXEC) contains pointers used by the EXEC for loading graphics, establishing timed tasks, and so on. You can change where the UDB lives by writing its address to location $2F0 and re-initializing the EXEC.

 

The 3 separate sub-games in Word Fun each have their own UDB. When you pick one of the games, the launcher rewrites the UDB pointer and reinitializes the EXEC, so that the EXEC can load the pictures and such associated with the sub-game.

 

Because those second-level UDBs don't have title screens associated with them, they don't set copyright years or anything else. When the launcher asks the EXEC to re-initialize, it performs the lockout check again on this new UDB, and freezes at that point.

 

Whoa, that is a way more interesting reason why Word Fun fails rather than I expected.

[daldude]

All this did was piss Intellivision owners who had the Intellivision 2 off but companies found ways around it and re released their games to work on the INTV 2.

No Big Loss on Donkey Kong which sucked anyway.

[jlew715]

Some of the European releases of the Coleco games (i.e. CBS releases) had updated code that bypasses the lockout, which is sort-of weird because Coleco never (to my knowledge) re-released the games in North America with the updated code. The Intellivision II wasn't sold in Europe, so updating the code for European-only releases had no benefit that I can see.

 

Also, these INTV2-compatible European releases have three plastic chines which mechanically prevent them from being inserted into North American consoles. The carts themselves are fully compatible so sanding down the chines allows the Coleco games to be played in the Intellivision II.

[mr_me]

Coleco/cbs wouldn't have known if Mattel was making an Intellivision II for other regions. In fact there are some French secam intellivisions that have an intellivisiin ii chip set inside. I haven't heard of any pal intellivisions like that.