Question about third party intellivision games

[rhindlethereddragon]

I recently disovered that the ATARISOFT games completely bypassed Intellivision's built in operating system, and used an operating system that was right there on the cart.

 

Did Coleco, Parker Brothers, etc. use the Intellivision's operating system, or did they also use their own?

[catsfolly]

I recently disovered that the ATARISOFT games completely bypassed Intellivision's built in operating system, and used an operating system that was right there on the cart.

 

Did Coleco, Parker Brothers, etc. use the Intellivision's operating system, or did they also use their own?

the Intellivision had a built in rom with 4k of functions that could be called by the cartridge program. This was know as the Intellivision "exec". I wouldn't call it a complete operating system, just some useful code. Since the early cartridges were limited to 4k themselves, anytime they could use a function in the exec, it saved space in the cartridge for other code and graphics.

 

On the other hand, the exec code was general purpose code designed to work for many kinds of games. It generally updated the hardware and motion objects 20 times a second. Also, Mattel considered the exec functions a trade secret and never released the details about how to use these functions. And, larger ROM cartridges became possible and memory space was not so critical.

 

So, most third party companies (then and now) ignored the exec and wrote all their own code. This way they could optimize the code for their particular game, and the didn't have to wrestle with undocumented exec code.

 

David

[+DZ-Jay]

I recently disovered that the ATARISOFT games completely bypassed Intellivision's built in operating system, and used an operating system that was right there on the cart.

 

Did Coleco, Parker Brothers, etc. use the Intellivision's operating system, or did they also use their own?

the Intellivision had a built in rom with 4k of functions that could be called by the cartridge program. This was know as the Intellivision "exec". I wouldn't call it a complete operating system, just some useful code. Since the early cartridges were limited to 4k themselves, anytime they could use a function in the exec, it saved space in the cartridge for other code and graphics.

 

On the other hand, the exec code was general purpose code designed to work for many kinds of games. It generally updated the hardware and motion objects 20 times a second. Also, Mattel considered the exec functions a trade secret and never released the details about how to use these functions. And, larger ROM cartridges became possible and memory space was not so critical.

 

So, most third party companies (then and now) ignored the exec and wrote all their own code. This way they could optimize the code for their particular game, and the didn't have to wrestle with undocumented exec code.

 

David

 

What you say is true, but I would add that the EXEC was more than just a few routines: it was rather more like a game engine. It handled graphics, sprite animations, controller input, music, sound effects, etc. The programmer had to prepare data structures in EXEC-friendly format, stored them at the expected locations, and the EXEC would take care of everything. It also contained routines that the game code could use to perform common functions, such as distance and physics. About the only thing the programmer needed to do was write the game logic itself. It made developing games faster and more streamlined.

 

Of course, this level of abstraction in such a primitive system came at a price: the refresh rate was half of what the device could handle, the input handling was wonky, and graphics were rather simple. It also made most games look and feel the same. This is why programmers broke out of the confines of the EXEC as soon as they felt confident enough to work directly with the hardware.

 

-dZ.

Edited March 11, 2011 by DZ-Jay