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Al Hartman
September 29th, 2013, 10:29 AM
I upgraded my Atari 520-ST to Rainbow TOS 1.04 from the 1.02 that was in the unit.

1.04 (RAINBOW TOS) Many bug fixes, file selector changed, DOS-compatible disk formatting, much improved performance. However, compatibility problems with older software.

Most common version of TOS; last version to run on pre-STe machines; most compatible with games. More bug fixes (e.g. archive attribute works); improved hard-disk handling and performance. Faster disk copy; file move function; copy preserves date/time stamps; folder renaming; auto-run of GEM apps at startup; larger screen support; file "fastload" flag for faster startup; improved file selector; DOS-compatible disk format; keyboard reset. AKA "Rainbow TOS" because of animated colour Atari "Fuji" logo in desktop "About" dialog box.

I got my set on eBay, though you can download the code and burn your own. By the time you buy 6 EPROMS, and get the code and burn them, buying them is easier.

All I had to do was swap the chips already in the unit for the new ones. From front to back, L0, L1, L2, H0, H1, H2

Next is to fix my AERCO EASIE-ST RAM upgrade. I ordered some 16 pin sockets. I'm going to remove the two piggy-backed headers from the chips, install two sockets soldered to the chips, and plug the headers into the sockets.

I'm hoping that will fix it. Then, I need to find the instructions to take the board up to 2 megs.

http://www.sarnau.info/files/RainbowTOSReleaseNotes.pdf

SiriusHardware
June 30th, 2014, 11:56 AM
I upgraded my Atari 520-ST to Rainbow TOS 1.04 from the 1.02 that was in the unit.

1.04 (RAINBOW TOS) Many bug fixes, file selector changed, DOS-compatible disk formatting, much improved performance. However, compatibility problems with older software.

Most common version of TOS; last version to run on pre-STe machines; most compatible with games. More bug fixes (e.g. archive attribute works); improved hard-disk handling and performance. Faster disk copy; file move function; copy preserves date/time stamps; folder renaming; auto-run of GEM apps at startup; larger screen support; file "fastload" flag for faster startup; improved file selector; DOS-compatible disk format; keyboard reset. AKA "Rainbow TOS" because of animated colour Atari "Fuji" logo in desktop "About" dialog box.

I got my set on eBay, though you can download the code and burn your own. By the time you buy 6 EPROMS, and get the code and burn them, buying them is easier.

All I had to do was swap the chips already in the unit for the new ones. From front to back, L0, L1, L2, H0, H1, H2

Next is to fix my AERCO EASIE-ST RAM upgrade. I ordered some 16 pin sockets. I'm going to remove the two piggy-backed headers from the chips, install two sockets soldered to the chips, and plug the headers into the sockets.

I'm hoping that will fix it. Then, I need to find the instructions to take the board up to 2 megs.

http://www.sarnau.info/files/RainbowTOSReleaseNotes.pdf

Quite an old thread now but I don't doubt that someone else will be following in your footsteps every now and then.

You're right that the Rainbow TOS breaks compatibility with some programs which worked under earlier TOses: One such was the original copy of ST Arkanoid which came in the software bundle I got with my 520STFM. Under the Rainbow TOS, the mouse left-right control ceased to work.

I actually went so far as to analyse why this was and found that there was a RAM location in which the system kept a record of the mouse x-co-ordinate - the Arkanoid code was reading that location to get the mouse X position, but it turned out that in the rainbow TOS, this 'live' value for the mouse X position was maintained in a different RAM location. In those days I was keen, so I hunted down the corresponding RAM location in the Rainbow TOS, copied the Arkanoid disc and patched the copy so that it would read from the location used by the new TOS.

However, I couldn't face doing that for every item of software which didn't work under TOS1.4.

In my 520STFM the original TOS was in 6 * 27256 proms, so the logical replacement was a set of 27C256 eproms programmed with the relevant segments of the Rainbow TOS code. However - I realised that if I used 6 * 27C512 eproms instead, I could program the old TOS into the lower halves of all the chips and the new TOS into the upper halves, bend all the pin 1 pins (A15) of the chips straight out horizontally, plug all the chips into the relevant sockets (ensuring that the pin 1s did NOT go into their relevant holes in the sockets), wire all the EPROM pin 1s together and take them via a switch to either 0V (= old TOS) or 5V (= new TOS).

This simple method worked (and still works) really well, but be aware that the system will crash instantly if the TOS switch is flipped while the machine is running: The cleanest time to do it is whilst holding in the reset button. With a bit of extra logic or a microcontroller it could be arranged so that the TOS switch position was not read and acted on until a hardware reset occurred, but I did not bother to do that.

You're also right to say that the new TOS is well worth upgrading to - in my opinion the improvements to hard drive access speed in particular were nothing short of spectacular.

Al Hartman
June 30th, 2014, 12:25 PM
I did fix the AERCO Easie-ST RAM upgrade board so that I now have a 1mb unit. Someday, I'll buy the chips to take it up to 2.5mb and find the documentation to max it out at 4mb.

SiriusHardware
June 30th, 2014, 12:39 PM
I updated to 2.5MB back in the day when my ST was still my main machine - I can't remember who that version of the upgrade was by (we're talking 18 years ago now!).

It works OK but the solderless construction (it's basically installed by shoving things into existing sockets alongside the chips which are already there) make it a little bit physically unstable.

As long as I don't bounce it off the floor, it keeps working, but I have occasionally had to take it apart to re-seat the RAM upgrade.