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520ST boots from gotek but 2 Bombs while loading TOS from ROM


Boteb

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Hello there, 

i'm new at this forum and like to ask a question. I've bought a 520ST with a piggybag memory expansion. This machine boots from gotek (games, and tos from disk) But when i don't connect the gotek the machine shows a white screen with 2 bombs and then reboots continuous.  When i connect the diskdrive the result is the same. TOS from ROM won't start.
I've done the following for resolving the issue but with no result.
1. reseated and cleaned the roms
2. reseated and cleaned the 38 and 38a chips

 

I hope someone can help me with this. 

Thanks in advance.

 

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16 hours ago, Boteb said:

When i connect the diskdrive the result is the same. TOS from ROM won't start.

Are you doing this when the ST is already powered on, if so, it won't recover from the earlier

failures, you need a clean boot with the gotek attached.

 

Not sure why you get the bombs with no drive attached, may be down to an old version of TOS

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Actually it is TOS 2.06 which 'bombs' with no drive attached, or no disk in drive.

And it needs extra logic in STs . So, not likely.

If it is very old ROM, what only boots TOS 1.00 from floppy with it, should see this:

BootFfloTOS.png.8a70a6cb5415c2f0f551dea4ec38f75a.png

 

Looks rather as TOS chip failure - some of ROMs, EPROMs might gone bad.

Can you make a sharp photo of ROM chips, where printing on them is readable, so can know which exact TOS version is it ?

 

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  • 3 weeks later...

Ok...i've managed to burn a new 6 Rom serie i've found a set splitted on internet. (hard to find an allready splitted version). THis is an US 1.04 version.

The machine boots now. :)
I'd like to know if the video output related to the language of the rom's. The video output is now NTSC. I like to have a PAL version.
If this is the case then i have to split and burn new EPROM..

 

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The ROM's differ and the RF output is certainly different, Composite will probably be different

too, but you won't notice this as most monitors will sync to either frequency.

 

Have a look at this thread, seems to explain the main differences.

https://www.atari-forum.com/viewtopic.php?t=16699#:~:text=Hardwarewise%2C the only difference between,games%2Fdemos run in 50Hz.

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8 hours ago, Boteb said:

Ok...i've managed to burn a new 6 Rom serie i've found a set splitted on internet. (hard to find an allready splitted version). THis is an US 1.04 version.

The machine boots now. :)
I'd like to know if the video output related to the language of the rom's. The video output is now NTSC. I like to have a PAL version.
If this is the case then i have to split and burn new EPROM..

 

 

The video output is not governed by the ROM - except for the default video refresh rate in color mode.

 

Changing from a U.S. ROM to a European PAL ROM will change your keyboard mappings, and it will change the default video timing from 60hz to 50hz, but it will not change the color carrier signal from NTSC to PAL.   That last part is governed by the physical hardware on the motherboard.   Changing it is not trivial and probably not worth the effort.

 

I would expect most of the regulars here use RGB.   RGB can be either 50hz or 60hz, but you can also software switch it.   Most RGB monitors don't care either way.   Most scalers don't care either.   Some games do care though and will flicker if the refresh rate is not what they were coded for.

 

Composite color output is PAL or NTSC.  As stated, changing the ROM won't change this.   You'll just end up with NTSC at 50hz and unless your composite color monitor can handle the color signal you'll end up with a black and white image.

 

Mono mode is the same in both NTSC land and PAL land.

 

 

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Ok .. thanks all for the information and the ROMS !  I've ordered a UV Lamp to reset the EPRoms :) .  I thought to do this with sunlight but that takes weeks to reset especially in the Netherlands :). I'm a newbie at this.
Thanks all voor this flying start. 




 

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I've blanked the eproms with my 18W pond UV-C light :) 5 minutes total. I did not think about this yesterday.

The roms programmed with the files of snarkdluG and are working now. Next to this the PAL/NTSC issue is also solved !!.
I use the composite at this moment and wil solder a RGB cable 
tonight. Thanks again for all your support.


 

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