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Are the 128 bytes of RAM in the RIOT chip?


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#1 Random Terrain OFFLINE  

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Posted Thu Jun 14, 2018 3:44 PM

Are the 128 bytes of RAM that the Atari 2600 uses in the RIOT chip? If so, what is the correct wording? Is it in the chip or on the chip?

 

Thanks.



#2 Random Terrain OFFLINE  

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Posted Thu Jun 14, 2018 4:10 PM

Also, Atari Age magazine said that "its job is to read the information fed into it by the control switches and the joysticks." If it contains the RAM that the Atari 2600 uses, it's doing more than that. I'm adapting the text from that Atari Age article and would like to add a sentence or two that explains more about the RIOT chip in a simple way for non-programmers to understand.

 

Does anyone feel like posting about it or providing a link to a simplified explanation of what the RIOT chip does? I assume that it also reads the paddles and keyboard controllers, so I should probably change "joysticks" to "controllers."



#3 jaybird3rd ONLINE  

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Posted Thu Jun 14, 2018 4:48 PM

Yes, the 128 bytes of RAM is in the RIOT chip, which is just an off-the-shelf 6532.  According to the datasheet, RIOT stands for "RAM-I/O-Timer", and it was used in pinball machines and several Atari 8-bit computer peripherals as well as the 2600.  As its name indicates, it contains three features: the 128 bytes of RAM, two 8-bit digital I/O ports (in the 2600, these were used for the joysticks and console switches), and a programmable interval timer (this can be thought of as an automatic counter which generates an output signal when it reaches a specific value; by programming it with different starting values, you can create intervals of different lengths).



#4 Osgeld ONLINE  

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Posted Thu Jun 14, 2018 5:08 PM

well its in the black chunk of plastic we call a chip, its on the silicon wafer inside the package 

 

so whatever 



#5 Random Terrain OFFLINE  

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Posted Thu Jun 14, 2018 7:44 PM

I was doing some more Googling and found this page:

 

Atari Hardware Explained



#6 Keatah OFFLINE  

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Posted Fri Jun 15, 2018 2:32 AM

In the chip or on the chip are both fine. It just depends what your point of view is and what you consider the chip. The die substrate alone, or completed 40-pin black plastic DIP.



#7 Mr SQL OFFLINE  

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Posted Fri Jun 15, 2018 8:40 AM

Interesting semantics - we have games on tape and games on disk and games on cartridge, but it's awkward to say the files are in the disk since they are in magnetized particles on the disk.

 

Depending on the context we can refer to a format with in pretty naturally; the game is "in ROM" or "in RAM" or "in a wave file". Then there's another context change from there - the ROM or RAM is on the cart when cart means daughter board but it is in the cart if the connotation is housing for the daughter board.

 

The context change for the wave file doesn't work as naturally; the game is encapsulated in the audio format certainly and the audio is stored in the magnetic particles (more format encapsulation) but they are decidedly on the disk or tape and not in it unless we change context again and refer to disks and tapes as the plastic housing containing the actual disk or tape; euphemistic as the meaning is lost.



#8 DirtyHairy OFFLINE  

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Posted Mon Jun 18, 2018 12:25 PM

RT, the blogpost you quote pretty much sums it up. Nothing to add :) The 128 bytes RAM are part of the RIOT. Whether you call it "in" or "on" the chip is splitting hairs imho.



#9 carlsson OFFLINE  

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Posted Mon Jun 18, 2018 1:02 PM

The I/O ports though are on the chip, not in the chip, meaning they connect to the outside? Then again the RAM also has an interface to the outside, otherwise the CPU wouldn't be able to use it... :)



#10 jmchacon OFFLINE  

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Posted Mon Jun 18, 2018 4:58 PM

The I/O ports though are on the chip, not in the chip, meaning they connect to the outside? Then again the RAM also has an interface to the outside, otherwise the CPU wouldn't be able to use it... :)

 

Technically the I/O "pins" are on the chip. The I/O port mechanism is clearly in the chip or else you've just got some dead pins that won't work :)






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