Installing Atari Rainbow TOS


This morning I finished up installing Atari “Rainbow” TOS 1.4 in my Atari 1040ST.

I say “finished up” as the process began a couple weeks ago when I’d discovered a set of Rainbow TOS 1.4 upgrade ROMs on eBay. The auction stated to specify whether I required the two ROM or six ROM version. Not knowing this information off hand, I needed to rip the 1040ST apart and find out.

Getting to the TOS ROMs was surprisingly difficult. On the 1040ST, they’re located deep within the bowels of the computer, underneath the power supply. To get to them required a complete disassembly of the system, removing numerous screws, RF shields (with little twisted metal locking tabs), connectors, the power supply, etc . Once I’d done all that and confirmed I needed the six ROM set, I set the whole pile of parts aside until the ROMs arrived - it was a lot of work tearing it all down and I didn’t feel like reassembling it and doing it a second time a few days down the road.


Yesterday afternoon the new TOS ROMs arrived. They shipped in the original, unopened package just as dealer would have received directly from Atari. In fact, the supplied documentation stressed that this was a dealer, rather than end user install. Being that this is 2008 and all, we’ll throw that advice to the wind.

Since the machine was already gutted, swapping the chips out was straight forward, but figuring out where all the various sized screws went two weeks on was a bit challenging (yeah, I know - should have taken notes). I also had a bit of clear plastic sheeting left over - looks kind of like it was meant to isolate the power supply from the RF shield, but I couldn’t puzzle out how it was supposed to fit. No matter - off to the wind with you, odd bit of plastic!

Once everything was reassembled, the machine booted into TOS 1.4 without complaint. The “About” dialog on TOS doesn’t give version numbers like most other operating systems, but you can verify the version by the copyright dates. The old TOS 1.0 I removed was copyrighted 1985, and the new TOS 1.4 in 1989.


The Atari ST is kind of an odd duck in that the entire operating system is supplied on ROM rather than diskette. So why bother to upgrade to this newer version? Primarily for the MS-DOS diskette read/write/format compatibility - this will make it a lot easier to swap files back and forth between a modern internet capable machine and the ST. There are also other sundry features and bug fixes rolled in which makes this a worthy upgrade all around.


I am curious about this TOS, is this basically an unreleased version? Where does the name "Rainbow" come from?

I ask because I know Atari was working on a "Rainbow" system around this time. According to Jack Palevich (the author of Dandy) this actually referred to the GPU, and the machine as a whole was known as Eva.

FYI: WordPress login doesn't work. I had to blow the dust off my OpenId.

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This page contains a single entry by nekonoko published on September 17, 2008 6:01 AM.

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