6 chip TOS

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Captain Atari
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6 chip TOS

Postby Methanoid » Sun Feb 11, 2018 5:31 pm

I have an ancient but functional 520 STM. Its got a (fault so removed) 512k Ram upgrade and 6 chip TOS 1.00 but with zero pads for upgrading to 2 chip TOS.

Rather than make life difficult with bending pins and adding OR gates etc.. is there an easy guide I can pass to my friend-with-Eprom-burner to burn me a 6 chip TOS set?

Is TOS 1.04 the best I should fit for an old ST?

My mobo has different labels for the chips to others I can find so I need to know how we split the image into 6 chip images and then which chip goes in which socket, please


Obsessive compulsive Atari behavior
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Re: 6 chip TOS

Postby Zippy » Mon Feb 12, 2018 1:19 pm

If you're stuck you could dump the 6 chips you have and compare them to the single part image for TOS 1.00 and work out from that how to split the TOS 1.04 image for the 6 chips. If the device programmer software is any good it should have options for loading data from an offset and specific length in the file without even having to split the file at all.

There's some more info here:

http://www.atari-forum.com/viewtopic.ph ... 9&start=25

but I'd mark and dump the existing 6 chips to be 100% sure the new ROMs will be mapped correctly.

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Captain Atari
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Re: 6 chip TOS

Postby Bama » Tue Feb 13, 2018 3:30 am

I think we have an Atari App to split the TOS files. Maybe on Ppera’s website????


Here is his posting.


Updated hyperlink to his most excellent utilities:

Last edited by Bama on Tue Feb 13, 2018 12:49 pm, edited 1 time in total.

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Re: 6 chip TOS

Postby ranix » Tue Feb 13, 2018 4:45 am

I think tos 1.04 is good for an old ST, it's what I've been using. I have a 6-chip 1.04 TOS set I got off Ebay for a song. I've swapped it out with the Exxos fast TOS upgrade (which isn't working perfectly for some reason, but that's another story).

iirc I had to ship my TOS set from the UK so it will probably be cheaper for you

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