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Adonick

Is the 2600 4bit or 6bit?

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I argued with a friend that the Atari is a 4bit system, though I may be wrong. I think his guess of six seems unlikely, since it seems to go in multiples?

 

Anyone clear this up with reasoning?

 

Nick

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Love it when this question comes up. There are no programmable video games systems that use 4-bit processors. Every system is at least an 8-bit.

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Wow. When you consider the NES is 8 Bit, I was assuming it would have been a generation before that.

 

Thanks for the info!

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Yeah, but Microvision isn't a video game system. :P

 

Unless you found some way to hook it up to your TV. :D

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Yeah, but Microvision isn't a video game system.   :P  

 

Unless you found some way to hook it up to your TV. :D

By that standard, the Lynx isn't a video game system either. :roll:

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Yeah, but Microvision isn't a video game system.   :P  

 

Unless you found some way to hook it up to your TV. :D

 

It came with its own TV - though you could only get the Microvision channel which was low resolution :D

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Wow. When you consider the NES is 8 Bit, I was assuming it would have been a generation before that.

 

There were 8-bit processors before Atari and there are still devices that use 8 bit processors today (several PIC processors we use in embedded development are in that realm).

 

All that an "8-bit processor" really implies is that the native data line and address line memory access and all associated registers are 8-bits wide (and even then it can be misleading as some processors have an 8-bit data bus and a 16-bit address bus, etc). The Dreamcast uses a 128 bit processor. The XBOX uses a 32 bit processor. Using the native word size (i.e. 8-bit, 16-bit, etc) as an indication of raw performance power can be very misleading. Even knowing the native word size and the processor speed is not nearly enough - you need to factor in the efficiency of the instruction set, the bandwith and off-chip processing for video output, any off-processor peripherals that may help with sound generation, etc. It's a total package that needs to be evaluated. But since most folks don't think in terms the whole package and since _roughly_ the consoles used processors that generally increased in word size as they became more powerful we are left with defining video game eras as "the 8-bit era" and the "16 bit era" but clearly there is overlap and cross-positioning since processor word size alone doesn't correlate 1:1 with console power.

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Yep, it's 8-bit. Which has nothing to do with why the graphics are so primitive. That's because the TIA is a 1-dimensional graphics chip. Yep, 1D. It only remembers enough information for a single scan line. That's why a locked up 2600 will display a lot of vertical lines.

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When you look at "bits", it gets very misleading. Here is a breakdown of processor bits:

 

Data Bus - How large can the numbers be that the processor can receive at a time?

Address Bus - How much memory can a processor access?

Instruction Set - How many instructions can a processor have?

Register Size - How large can the numbers be that the processor will work with?

 

With the 6507 (Atari 2600 processor), the answer is:

Data Bus- 8-bit

Address Bus - 13-bit

Instruction Set - 8-bit

Register Size - 8-bit

 

By contrast, consider the modern Pentium 4 (without x87, MMX, or SSE1-3):

Data Bus - 64-bit

Address Bus - 36-bit

Instruction Set - 16-bit

Register Size - 32-bit

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And we won't even mention the Intellivision.... which, for those who are curious, is a 16-bit CPU but uses 10-bit ROMs - most CP1610 instructions are 10 bits wide so why bother using the 16-bit ROMs? Lovely.

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Yep, it's 8-bit.  Which has nothing to do with why the graphics are so primitive.  That's because the TIA is a 1-dimensional graphics chip.

On the other hand, the 2600 can actually display over twice as many colors as the NES (128 vs 52).

 

But yes, the Atari 2600, 5200, and 7800 are all 8-bit systems. In fact almost every home computer manufactured before the Amiga era was 8-bit.

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