exxos's Atari, Amiga & retro forum

Hi Forum,
I have refreshed an Atari 1040STFM and wanted to run my new satandisk but seems my TOS version is too low. The device boots from satandisk after reset but files in folders are not accessible. Empty folders. I believe it is 1.0 or 1.02. Cannot run sysinfo to validate. Will try again. Files on SD show up 100% ok on Mac.

Now I want upgrade the two TOS Chips to 1.04 and need a source. Seems not easy to find two chip version. I enclose pic of my motherboard and also zoom in on tos chips.

Is 1.04 recommended or TOS switcher. I don’t want to drill any holes in housing or any other switches hanging out etc.

Any idea where I can buy them at as always most reasonable price. Thanks.

BR

Mathias

It's basically impossible to find 2 chip TOS104 original. I used to sell chips you could hack in but I stopped doing that as it was messy.

Probably the best bet is to just solder in the other ROM sockets and convert to 6chip TOS.
Basically do this in reverse
https://exxosforum.co.uk/atari/last/tos ... m#TOS6CHIP
https://www.exxosforum.co.uk/atari/store2/#0119

You could either get a TOS switcher such as this: STFM Dual TOS switcher or this: STFM Dual TOS switcher SMT version

Either would allow you to use say TOS 1.02 & TOS 1.04 together, however if you wanted to use TOS 2.06 you'd also need one of these: TOS 2.06 decoder

However, you have a surface mount board without sockets which would make use of the decoder rather more difficult to do, if at all.

If you simply wanted to upgrade to TOS 1.02/1.04 dual TOS you'd be fine as your ROMs are socketed.

If you just wanted to go to TOS 1.04 then you could easily burn a 6 chip set to install instead of the 2 chip set you have, and there are examples of how to do this on the site.

You'd need 6x27C256 ROMS and 4 extra sockets plus 4 decoupling capacitors, then change the ROM jumper pads from 1M to 256K. The ROMs can be found easily online or you can use a ROM splitting tool to break the images into 6 inside an emulator like Hatari and that would also correctly name them.

On a normal ST I'd not go beyond 1.04 to be honest as there's little point.

The ROM switcher board with a dual ROM set to use a single image sounds like the simplest, easiest and most foolproof way of upgrading the system.

The dual TOS board you'll need is the first one (having reviewed the images).

You can get these TOS 1.04 chips here:

https://www.ebay.com.au/itm/145251465963

There are not original though...

I may have original ones somewhere in my Atari related boxes.

I was faced with exactly the same problem a month ago, the solution was reasonably simple (IMHO easier than task of clearing 128 holes and fitting 32K EPROMs). But I wanted to be able to switch between TOS v1.2 and v1.4

I used two 27C2001 EPROMs (256Kx8) with pins 1,2,30,31,32 bent out, pushed the chips into the sockets and wired the pin 1,31,32 to Vcc, wired pin 2 to A17 and pin 30 to a switch. The crafty fix was by changing blob of solder from 1M to 256K on the 'A17' pad you ground 20 (EPROMs /E) and can pick up A17 from unsoldered pad (to go to pin 2s).

If you don't want dual TOS then it is simpler: using two 27C1001 (128Kx8) pin 30 (NC) doesn't need to be bent out, it can be left to plug into Vcc. Pins 1,31,32 to Vcc (i.e. capacitor leg). Swap blob on 'A17' and pin 2s to pad. I can post photo of mod if interested.

Hi Everybody,

wow, seems a lot more complex than put in two 1.04 ROMS. Ok, it is what it is.

So I am not the big mod fan, so probably will insert four more sockets and get the 6 Rom 1.04 ROMS from somewhere, as I have no EPROM Writer to split and write the 1.04 into 6 EPROMS. I am hopeful I can buy the six chip TOS somewhere here in Germany.

I truly appreciate everybody's support and contribution to help me understand my situation and recommend several cause of action.

All have a great day.

Thanks again.

exxos wrote: 29 Apr 2024 09:21 It's basically impossible to find 2 chip TOS104 original. I used to sell chips you could hack in but I stopped doing that as it was messy.

Probably the best bet is to just solder in the other ROM sockets and convert to 6chip TOS.
Basically do this in reverse
https://exxosforum.co.uk/atari/last/tos ... m#TOS6CHIP
https://www.exxosforum.co.uk/atari/store2/#0119

A quick question, when doing the above in reverse (converting from a 2 to 6-chip ROM setup), do I need to remove the 74LS11 at U68 or can I leave it in place? It says in the article that on 6-chip machine " U68 may or may not be missing" so I'm assuming U68 can stay in place?

nigcube wrote: 16 May 2024 23:18 A quick question, when doing the above in reverse (converting from a 2 to 6-chip ROM setup), do I need to remove the 74LS11 at U68 or can I leave it in place? It says in the article that on 6-chip machine " U68 may or may not be missing" so I'm assuming U68 can stay in place?

The chip doesn't matter. Its configured by solder jumper pads to use it or not. notice the 256K /1MB solder pads next to the ROMs..