Non working new MOS 6502 in Atari 800

[spudmanno5]

Hi

 

I got a new MOS 6502 from this guy (basically same auction link):

 

http://cgi.ebay.co.uk/MOS-6502-A-2-MHz-CPU...id=p3286.c0.m14

 

As you can see he claims the slightly higher clocked CPU will work in an Atari 800. Now when i tried it in mine all i got was a brown screen nothing else. Yet i put the old one back in and it seems to work fine again. I repeated the process - same result. I contacted the guy stating this and he didnt know wot was wrong with it so he gave me a refund. Anyone know if this CPU will actually work on Atari 800s?

 

Regards

[Sub(Function(:))]

Hi

 

I got a new MOS 6502 from this guy (basically same auction link):

 

http://cgi.ebay.co.uk/MOS-6502-A-2-MHz-CPU...id=p3286.c0.m14

 

As you can see he claims the slightly higher clocked CPU will work in an Atari 800. Now when i tried it in mine all i got was a brown screen nothing else. Yet i put the old one back in and it seems to work fine again. I repeated the process - same result. I contacted the guy stating this and he didnt know wot was wrong with it so he gave me a refund. Anyone know if this CPU will actually work on Atari 800s?

 

Regards

 

Possibly not, the problem is the atari 6502 has some extra buffers connected to some of the pins (this is internal to the CPU package). some one will know the details

[+warerat]

Depends on the CPU board revision you have. If it's CO15500 it takes the same SALLY 6502C as the XL/XE. That rev has a single 74LS244 on board. I bought a whole lot of 800s and only a couple had that kind of CPU board. I can only speak for NTSC machines.

 

Otherwise, assuming the CPU in the picture is the same, I have used that Synertek 6502A in the older-rev CPU board with no problems as they take stock 6502 chips.

[+bf2k+]

I replaced the original chip in my first 800 - pretty sure it was a regular old 6502C.

[ClausB]

My 1980 400 came with a 6502B. Not sure why they used a 3 MHz part in a 1.8 MHz machine, maybe marginal timing somewhere in the design? Maybe just better availabality at the time? Anyone know?