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Intellivision TutorVision found w/games


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#126 intvnut OFFLINE  

intvnut

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Posted Wed Apr 12, 2017 10:26 AM

I think it's an Intellicart.  I think I can see a white cable coming out of the cartridge going to the Mac right beside it.

 

Yeah, I was thinking the same thing.  It's hard to tell at that image resolution. 

 

 

Now about the Tutorvision sound chip.  When you say it sounds like the original 1978 Intellivision, is that different than the 1980 Intellivision?

 

I'm saying it's closest to the original AY-3-8914 in terms of how the registers behave.  The most noticeable behavior is the behavior of "count == 0."  That seems to be the source of "thin sound" complaints on some Intellivision 2s.  The STIC1A behaves more like the AY-3-8914 here, giving a maximal count for "count == 0."

 

 

And regarding jzintv did you put a switch to turn on/off extra gram like Decle's -G2 switch or is it only automatic?

 

both.png

 

If you provide jzIntv the WBEXEC/WBGROM, it will default to TutorVision behavior.  You can also explicitly set the GRAM size with the -G flag.



#127 Lathe26 OFFLINE  

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Posted Wed Apr 12, 2017 10:50 AM

Awesome work and attention to detail, jz.  This is all really cool!



#128 intvnut OFFLINE  

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Posted Thu Apr 13, 2017 11:44 PM

You can also explicitly set the GRAM size with the -G flag.

 

It appears I made a minor flub and the -G switch isn't recognized.  You can use the long version of the switch, though: --gramsize=#.

 

I'll post an updated executable in the next couple days that supports the -G switch as well.



#129 mr_me OFFLINE  

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Posted Sat Apr 15, 2017 5:12 AM

OK, I finally got jzIntv updated for Windows and Mac.  It turns out that my emulation wasn't complete, and I needed to make a few more changes.  I discovered a few more quirks of the TutorVision system.
 
http://spatula-city.org/~im14u2c/intv/
 
Note that I have not yet updated the Linux build, as my Linux box is still offline.  I hate living in this cramped apartment.
 
I've also posted extensive reverse engineering notes here.  This is still a work in progress.
 
EDIT:  The PDF posted in the next comment is much more readable.

So there's an extra pixel and some different bus times. Any chance this STIC offers new features. There's enough ram for 24 rows of characters.

There's something about slightly different bus times. Would that not affect existing games. Something about gram aliases that does affect some existing games. Did you put these changes in jzintv?

#130 intvnut OFFLINE  

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Posted Sat Apr 15, 2017 5:32 AM

So there's an extra pixel and some different bus times. Any chance this STIC offers new features. There's enough ram for 24 rows of characters.

 

No evidence at all of any new features beyond what I've documented.  You get some extra GRAM and the incompatibilities that come with it.  :P   And, MOBs aren't limited to 64 cards in FGBG mode.

 

 

There's something about slightly different bus times. Would that not affect existing games. Something about gram aliases that does affect some existing games. Did you put these changes in jzintv?

 

The version of jzIntv I posted implements all of the STIC differences I'm aware of, including the different bus timings.  The "irq_per" test linked in my document produces roughly the expected result in jzIntv. 

 

The different cycle-stealing behavior would lead to some games running slightly faster.  Most games are timed off the vertical retrace, so they'd play the same speed.  If a game had a timing-related race condition, it might behave differently.

 

Also, since you asked me previously:  The STIC does fetch background cards from the 4 x 2114 RAMs during active display, using /BUSRQ to halt the CPU so it can fetch.


Edited by intvnut, Sat Apr 15, 2017 5:43 AM.





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