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C014806-03 vs C014806-12

C014806 xe xegs

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#1 adrm OFFLINE  

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Posted Tue Sep 4, 2018 8:09 AM

Hi.

 

I have just received my first Atari 8-bit computers; two PAL XEGS. One works, the other doesn't.

(I have ordered up replacement RAM for the faulty one.)

 

But my question is: What is the difference between the C014806-03 and the C014806-12 CPUs?

 

My guess is that the -03 is a 3MHz chip for use in PAL units (this is what I have in my XEGS') and that the -12 is the 2MHz version for use with NTSC units.

I'd be grateful for a clarification, as I like to order up a few spare parts to have on hand.

 

 

Cheers,

Tore



#2 mytek OFFLINE  

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Posted Tue Sep 4, 2018 8:18 AM

All A8's use a 2 Mhz processor irrelevant of whether they are PAL or NTSC based machines. The suffix on the part numbers you showed has to do with manufacturing batch/date and nothing to do with speed. Either one should work.

#3 adrm OFFLINE  

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Posted Tue Sep 4, 2018 8:28 AM

Ahh, thank you.

 

The confusion came from a paragraph I found in a Service Manual for the Atari 400/800 computers which said:

 

The domestic 6502 operates at 2.0 MHz, and the PAL & UK 6502 operates at 3.0 MHz. The increased speed is required to operate within PAL & UK television standards.



#4 MrFish ONLINE  

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Posted Tue Sep 4, 2018 9:16 AM

All A8's use a 2 Mhz processor irrelevant of whether they are PAL or NTSC based machines. The suffix on the part numbers you showed has to do with manufacturing batch/date and nothing to do with speed. Either one should work.

 

I was just reading this thread the other day, which would point to otherwise. The 6502B's we see in 400/800's should be 3MHz.

 

Real Core of 6502C (Sally)



#5 mytek OFFLINE  

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Posted Tue Sep 4, 2018 10:13 AM

Thanks MrFish I stand corrected on the speed rating that became a standard for all machines after the 400/800 series. Apparently they were 3 Mhz rated parts by the time the custom '02 version (Sally) was created for Atari (although the discussion you linked to kind of goes all over the map about that). These also got used in the later 400/800 series as well, and it looks like there was a mixture of standard 6502 2 Mhz and 3 Mhz parts in use prior to the custom version coming online. But only a 2 Mhz speed rating was ever really required for either a PAL or NTSC machine to work properly (don't let the 3.5x crystal frequency fool you, since that gets divided in half before clocking the CPU).

The interesting thing is if Atari had used the 4 Mhz 6502 as the basis for their custom version, there might have been an upgrade path for a considerably faster machine based on the 3.5x crystal frequency not being halved. Although that would have required a faster version of the other custom chips as well.

Anyways back to the OP's original question... either part you specified will work in a PAL or NTSC machine. And I don't believe the suffixes on those had anything to do with speed.



#6 adrm OFFLINE  

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Posted Tue Sep 4, 2018 11:07 AM

Thanks, both.







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