Atarisoft -- Why two Commodore versions?

[else]

Okay, I'll admit I know very little about the Commodore line of computers. But why did Atarisoft publish separate versions off all their games -- one version for the VIC20 and another for the C64? I generally assumed the two machines were mostly compatible with each other (one just had more memory). Is this not the case?

[Nukey Shay]

Nope. Not even close. Not only were the 2 systems incompatable, but the Vic20 wasn't even capable of displaying even the most basic of screens found on other systems (due to the goofy 22x23 character display). It was capable of using most C= peripherals of the time (as were most of C='s machines), and executing very undemanding BASIC programs (ones common enough to run on any BASIC interpreter)...but that's it. As such, commercial software was totally incompatable.

[+evg2000]

see the difference?

commodore 64 donkey kong:

vic 20 donkey kong:

later,

Charles

[Nukey Shay]

Guess which is which...

[else]

Cool, thanks! Wonder why they didn't do more to make the two machines compatible with each other? Ah well, that's all ancient history I guess......

[doubledown]

Well the C-64 was released 2 years after the Vic-20.

[Seob]

The vic20 uses a 6502A processor, the c64 a 6510.

The vic20 also uses a larger game slot then the c64.

The vic20 was replaced by the c16.

More info here

Vic20

C64

C16

The presessor of the vic 20 was the vic-1001.

They all used the same case design. The c64 got an other case design later on arround 1987 that also was used for the c128.

[darthkur]

The presessor of the vic 20 was the vic-1001.

 

Actually the Vic -1001 is just the Japanese version of the Vic-20. They are the exact same computer other than small cosmetic differences. The actual predecessor to the Vic-20 was the C= PET series. Then the Kim-1 before that.

[+Random Terrain]

That's kind of like asking why companies released versions of the same games for the Atari 2600, Atari 5200, and Atari 7800.

[2600Lives]

They all used the same case design. The c64 got an other case design later on arround 1987 that also was used for the c128.

 

That's the C-64C version, I believe, with the 128 style case, only smaller. I have one, but it doesn't work (think it's a power supply issue).

 

For the most part, the Commodore 64 ports were amazing, and offer some of the best arcade conversions around, especially in the sound department. The VIC wasn't much for conversions, but the original games made for it are quite fun.

[else]

That's kind of like asking why companies released versions of the same games for the Atari 2600, Atari 5200, and Atari 7800.

 

Well, I thought it was more like asking why the Atari 400/800/XL series the Apple II/II+/IIe/IIc series didn't need separate versions for their different models -- two manufacturers I am more familiar with. Like I said, I know next to nothing about the Commodore line. I guess Commodore didn't worry so much about backwards compatibility as other companies did.

[Nukey Shay]

As mentioned, the C=64's architecture wasn't originally intended to be for a home computer. They had already sunk the money into developing it...so abandoning it at that point would mean more loss. In this case, the gamble turned out to be one of the greatest successes ever.

[+Random Terrain]

I guess Commodore didn't worry so much about backwards compatibility as other companies did.

Still, if we pretend that the Commodore 64 was supposed to be a computer and they made it play VIC-20 games, who would want to play the VIC-20 version of a game over a new Commodore 64 version that would have more colors, better graphics, and better sound?

 

Speaking of backwards compatibility, the Commodore 128 could run Commodore 64 programs.

[Dr. Van Thorp]

The original VIC graphics chip was developed by Commodore's MOS division with the intent of it being licensed to a game maker to compete against 2600/Intelivision are machines. This didn't happen. Then came rumors of upcoming Japanese machines that would kill the American market, so Commodore quickly re-engineered their PET computer to use the cheap VIC chip to produce a low-end machine that would beat the Japanese in price. The Japanese machine never arrived.

 

Then MOS's engineers went to work on another graphics chip. Two engineers compiled a list of all the features available in competitors' machines, and created a specification. The chip was the VIC-II, initially also intended for a game machine. This was combined with the SID sound chip, initially intended for a synthesizer, into a new machine with roots in the earlier VIC-20 and PET machines. The resultant Commodore 64 was compatible most VIC-20 peripherals, and had the same BASIC programming language, but outside of simple text-based BASIC programs, the graphics and sound were pretty much incompatible.

 

Remember that old 8-bit machines had minimal OS's; maybe 16-k or so or ROM, and maybe a couple of kilobytes of disk-booted DOS (which the Commodore machines didn't even have). So graphics and sound functions in games were mainly accessed directly through the hardware chips, without any application program interface between the programmer and the hardware. To make these two machines compatible in regard to graphics and sound would have been near impossible at that time.

 

Though I do recall one BASIC game, published in Compute magazine, that included some clever assembly language subroutines that simulated hardware sprites on the VIC-20 under special conditions to allow one game to run on both machines with minimal changes; an idea that could have changed everything but didn't take off.

[Chris++]

Else, you might be thinking of the C-64 vs. the C-128. The latter could run the former's software, but not vice-versa -- much like a PS2>PS1.

 

That 128 was the true jewel of the entire 8-bit era (but vastly under-used and under-supported, sadly).

[TwiliteZoner]

Else, you might be thinking of the C-64 vs. the C-128. The latter could run the former's software, but not vice-versa -- much like a PS2>PS1.

 

That 128 was the true jewel of the entire 8-bit era (but vastly under-used and under-supported, sadly).

 

I think Atarisoft did a pretty good job with those Vic-20 games.