Mega ST and exxos Decoder + dual tos problem

Upgrade or replace the ROM.
gwinter38
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Mega ST and exxos Decoder + dual tos problem

Post by gwinter38 »

Hi
Maybe somebody had contact with TOS 2.06 ST Decoder board from exxos ? I bought such a thing, together with the DualTos adapter 1.04/2.06. Assembled according to the art, the CE cables are connected as required and there is a problem. When switched on it shows the Atari logo, the 4mb memory test passes and ... suddenly 4 bomb. The flopy is connected and works. MegaST without decoder works ok, also with PAK030, reads and formats floppy diskettes and boots with ultrasatan. After inserting the decoder&dualtos you can enter the desktop 2.06 but only with the control button pressed at start. I also soldered out the FDD tape, inserted the socket and new cables. The computer does not start with the ultrasatan either. In STE I know that it may be a problem with the FDD not connected but in ST ?

J.Z.
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exxos
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Re: Mega ST and exxos Decoder + dual tos problem

Post by exxos »

Holding down control suggests its bypassing some software on boot up.. Have you tried with a blank floppy ?
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
gwinter38
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Re: Mega ST and exxos Decoder + dual tos problem

Post by gwinter38 »

I try everything. With control ( 2.06 ) always boots to the desktop. I also tried with a new CPU and replaced most of the chips from another MEGAST to rule out a malfunction, at the moment I put TF536 in and try to start with IDE but it probably won't work.
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PhilC
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Re: Mega ST and exxos Decoder + dual tos problem

Post by PhilC »

@gwinter38 if you're going to put a TF536 into your Mega then you will ultimately need to change the address and data bus pullups and maybe fit a couple of passives to the TF536 itself.

Also, when I fitted the socket to the decoder board i had not soldered some pins correctly and I do a lot of solder, so it may be worth fluxing up the socket pins and reflowing them just to rule it out.
If it ain't broke, test it to Destruction.
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Re: Mega ST and exxos Decoder + dual tos problem

Post by exxos »

Also if your machine had the blitter patch .. You haven't said about it..
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
gwinter38
Posts: 13
Joined: Sat Sep 12, 2020 11:36 am

Re: Mega ST and exxos Decoder + dual tos problem

Post by gwinter38 »

@exxos

There is no patch blitterpatch , but the blitter is pulled out for now. With and without blitter, it behaves the same way
gwinter38
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Re: Mega ST and exxos Decoder + dual tos problem

Post by gwinter38 »

@PhilC

I did not know that any additional modifications had to be made. This does not change the fact that even at 68000, the Mega ST has problems. It will be as I described it. At the moment I am pulling out the Decoder and ROM stand and I will try to improve the soldering points.
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PhilC
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Re: Mega ST and exxos Decoder + dual tos problem

Post by PhilC »

@gwinter38 just a couple of things to try.

Obviously back to basics, original roms and 68000 and make sure it boots then if your dual tos rom has 1.04 and Tos2.06 then put that in without the decoder and see if it will boot 1.04.
Then if that's successful then try with the decoder and tos 1.04 or original roms. No need to hook up CE wire for tos 1.04.

You mentioned you had the nlitter removed. Have you bridged the two jumper pads to tell the Mega that no blitter is present?
If it ain't broke, test it to Destruction.
gwinter38
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Re: Mega ST and exxos Decoder + dual tos problem

Post by gwinter38 »

little progress. the problem was probably the eprom socket. After the replacement, the MST is already starting to properly and boots with the fdd. The problem is still with the ultrasatan, but I will run the hddriver from the floppy disk and see if it starts up ....
gwinter38
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Re: Mega ST and exxos Decoder + dual tos problem

Post by gwinter38 »

Not exactly.
I tested the MST on the original configuration with DualTos adapter. It works with tos 1.04, it doesn't work with 2.06 and that's the way it should be. Computer boots with fdd, turns on correctly. The next step was, according to the advice, inserting a decoder. The computer does not get up properly.
TOS 1.04 - 11 bombs with the floppy disk inserted. Without the diskette in the FDD the computer displays GEM.
TOS 2.06 - without floppy in fdd , shows Atari logo, after memory test goes to GEM. With floppy diskette inserted in FDD - 4 bombs. When TOS 2.06 is activated without the floppy diskette, the FDD A icon is displayed when the GEM is activated. When I try to click on it, the computer hangs up and reboots. There is hddriver on floppy , it runs only when decoder is removed. I will also try to replace the cpu socket, but it's look ok
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