520ST / 520STM

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1632
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520ST / 520STM

Post by 1632 »

Hello,

On it's way is what I believe to be an STm. I certainly didn't buy it for collectibility/value as I know they're not worth much, it's just a nice one to own and will look good with my other STs :D

Anyway, a few things I was wondering :

Apart from the RF output, are there any actual motherboard differences between it, the original 520ST, and 260ST? For example, if the TOS ROMs were removed, would it function the same as a 'disk TOS' model? Might be a fun downgrade if at all possible.

Looking at images the badge appears to say 520ST not STm. I can't find any picture of one that says STm on the badge. Did STm appear anywhere at all on it (base sticker maybe...?)

I'd also read a few times the STm was released around 6 months after the original but that seems to be contradicted here : http://www.computinghistory.org.uk/det/ ... i-520-STM/ unless that refers to the UK release date.
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Re: 520ST / 520STM

Post by Zogging Hell »

The 'M' bit is on the lable underneath, has the same label as the 520ST on top. It's a nice machine, I actually prefer the design to the slightly larger STFM and STe. The desk clutter from the external disk drive is a bit of a pain, as is TOS 1.0 however...
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Re: 520ST / 520STM

Post by Zogging Hell »

BTW anyone else reading this topic :) I did wonder myself about the TOS Roms, what is deal with the disk loaded TOS versions? Is there a smaller ROM which just loads the disk rom? I always fancied downgrading one of my two STs, but could never find out if it was an early rom I needed. Is there even a rom image of the original ST disk loaded one if that is the case?
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520ST / 520STM

Post by Mal7921 »

The 520ST was released in Europe about 6 months after the 260ST and the STm was released after that along with the 520ST+ with 1MB RAM.

The only reason the 260ST exists at all is due to badges being made and RAM prices falling to a point where 512KB could be fitted and the machine still sold at the same price point that the originally planned 256KB model would have been released at. Only a few 260ST machines with 256KB shipped and most of those went to developers or were upgraded.

Now a 260ST with 256KB, that would be rare, assuming one still exists without being upgraded


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520ST / 520STM

Post by Mal7921 »

Zogging Hell wrote:BTW anyone else reading this topic :) I did wonder myself about the TOS Roms, what is deal with the disk loaded TOS versions? Is there a smaller ROM which just loads the disk rom? I always fancied downgrading one of my two STs, but could never find out if it was an early rom I needed. Is there even a rom image of the original ST disk loaded one if that is the case?
Originally the ST had some boot code in ROM somewhere for it to load the OS from disk. As the default ST behaviour is still to try and boot from floppy when powered on, I think that code is still there. As to where that code now is I could not say. It could now be part of the current TOS ROM in which case removing the chips will remove the boot code!

I've seen the original TOS floppy images on the Internet, though that was quite a while ago. If those can be found and made into a readable floppy disk again, you could just boot from those and experience the old floppy based TOS in all its buggy glory :-)


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Re: 520ST / 520STM

Post by nativ »

Well surely it is just the case of a 'bootsector' on the floppy to catch and load? Isn't that the way early games worked anyway?

Another thought? If a new smaller PSU was available? and you could replace the Floppy with an internal UltraSatan. and Incorporate an EtherNEC and. . . move the Joy/mouse ports to the side alá XEGS and early ST? Would you get that lot in a MK1 ST case? taking an STe mobo?

And can one be mocked up . . . ?
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Re: 520ST / 520STM

Post by Mal7921 »

nativ wrote:Well surely it is just the case of a 'bootsector' on the floppy to catch and load? Isn't that the way early games worked anyway?

Another thought? If a new smaller PSU was available? and you could replace the Floppy with an internal UltraSatan. and Incorporate an EtherNEC and. . . move the Joy/mouse ports to the side alá XEGS and early ST? Would you get that lot in a MK1 ST case? taking an STe mobo?

And can one be mocked up . . . ?
Are you suggesting these mods for an STfm/STe case or shoehorning an STe into an ST old style case? If it's the latter, you would need to make a whole new motherboard however if it is the former then the joystick ports could be moved with an internal cable and some handywork with a drill, though putting the ports on the back would be easier than in the side under where the floppy sits.

As for fitting an UltraSatan into a 260ST style case, yes there i room, though personally I'd leave the PSU alone and keep it outside the box.
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Re: 520ST / 520STM

Post by Foxxy74 »

Mal7921 wrote:
Originally the ST had some boot code in ROM somewhere for it to load the OS from disk. As the default ST behaviour is still to try and boot from floppy when powered on, I think that code is still there. As to where that code now is I could not say. It could now be part of the current TOS ROM in which case removing the chips will remove the boot code!

I've seen the original TOS floppy images on the Internet, though that was quite a while ago. If those can be found and made into a readable floppy disk again, you could just boot from those and experience the old floppy based TOS in all its buggy glory :-)


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If I recall correctly , my 260 ST lost 2 Eproms (<-- the guy named them so about almost 20 years ago ) when he replaced them with the rainbow-TOS ..

Still remember hunting down AUTO boot games, because they didnt need the TOS to play them I also think the 260 ST originally had 512 kb RAM , but after the TOS from floppy was loaded it lost lots of RAM, so almost none of the nicer games worked ..

Bought another (original) 260 ST .. still couldn't find the time to pick it up .. But in a few days i will :P gonna be my collectors piece.. !

:cheers:
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Re: 520ST / 520STM

Post by Mal7921 »

Foxxy74 wrote:
Mal7921 wrote:
Originally the ST had some boot code in ROM somewhere for it to load the OS from disk. As the default ST behaviour is still to try and boot from floppy when powered on, I think that code is still there. As to where that code now is I could not say. It could now be part of the current TOS ROM in which case removing the chips will remove the boot code!

I've seen the original TOS floppy images on the Internet, though that was quite a while ago. If those can be found and made into a readable floppy disk again, you could just boot from those and experience the old floppy based TOS in all its buggy glory :-)


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If I recall correctly , my 260 ST lost 2 Eproms (<-- the guy named them so about almost 20 years ago ) when he replaced them with the rainbow-TOS ..

Still remember hunting down AUTO boot games, because they didnt need the TOS to play them I also think the 260 ST originally had 512 kb RAM , but after the TOS from floppy was loaded it lost lots of RAM, so almost none of the nicer games worked ..

Bought another (original) 260 ST .. still couldn't find the time to pick it up .. But in a few days i will :P gonna be my collectors piece.. !

:cheers:
I managed to get a 260ST and a 520ST+ in the same auction from Germany, both boxed and apart from some yellowing of some, but not all keys, they are pretty much perfect. My STm is also boxed as well as my Megafile 44, but everything else has lost it's original packaging, which is a shame but nothing I can do about it now. It's more important that it works to be honest.

Enjoy the 260, admittedly it's not really any different to any other 512K ST, but it is diferent enough to be that little bit special :)
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Re: 520ST / 520STM

Post by Zogging Hell »

I think I have the original disk in my collection somewhere, I'll see if I can find it. It's a shame the original ROMs with just the boot code aren't available any where, would be funny to actually fit them in machine! (I have a memory upgraded 520ST, that would just love them..)
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Re: 520ST / 520STM

Post by Nyh »

1632 wrote:Apart from the RF output, are there any actual motherboard differences between it, the original 520ST, and 260ST? For example, if the TOS ROMs were removed, would it function the same as a 'disk TOS' model? Might be a fun downgrade if at all possible.
The original 260ST's had two ROM's that loaded TOS from disk. Later models had 6 ROM with TOS 1.0 in ROM.

You cannot down grade by removing the ROMs as you have to replace them with the TOS loading ROMs.

When you want to see how the TOS loading screen looked like then boot the TNT FNIL demo and do a warm reste (press the reset button). http://pouet.net/prod.php?which=22817

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Re: 520ST / 520STM

Post by 1632 »

Really interesting replies! Will check the TNT FNIL demo later.

So the question is, does anyone actually have/is anyone willing to dump these TOS loading ROMS? For curiosity as well as repair purposes - it seems a shame something so unique to the ST isn't available. I'd do it myself if I had the ROMs.
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Re: 520ST / 520STM

Post by SofiST »

TOS loading ROM is already dumped and there is a post about it in forum. I think that it is in "Other emulators and tools" section.
And it can be tried even with emulators, so no need for real ST (if it is problem). I patched it for Steem and Hatari. It is in same thread .
If can not find that thread, I will dig it out ...
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Re: 520ST / 520STM

Post by Zogging Hell »

Ooo thanks, will take a look!
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Re: 520ST / 520STM

Post by Zogging Hell »

Thanks found it after a bit of a search..

Now to put it on some roms!

http://www.atari-forum.com/viewtopic.php?f=8&t=18983
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Re: 520ST / 520STM

Post by 1632 »

If you do this, let us know how you get on - EPROMs used, how you split the file etc? :)
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Re: 520ST / 520STM

Post by Zogging Hell »

Sure, probably will be low on the todo list though, which is backed up with various fixes and installing blitter chips..
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Re: 520ST / 520STM

Post by 1632 »

Ah it was easy enough using 2 x 27c256 EPROMs...

It's probably very simplistic to most, but here was my method on a 6 chip TOS ST for anyone interested :

1. Dissect the 16kb 'tosload' file, 8-bit bytewise into tos.lo / tos.hi files - I used Winhex to do this.
2. Duplicate the resulting 8k files into 32k files to fill the 27c256 EPROM. I used Windows Command Prompt binary copy , i.e. : copy /b tos.lo+tos.lo+tos.lo+tos.lo tosx4.lo for each file. If the board is 2 chip TOS using 1 Megabit ROMs you'd just do the same a few more times to create a repeated 128k file.
3. EPROMs go in slots 1+4, they weren't marked 'HI / LO' on my particular motherboard so I just noted the correct way the notch should go and swapped them about till it booted correctly.
4. Enjoy the dodgy olden days Boot Screen, and wonder why you bothered as you could just have loaded the demo disk as recommended by Nyh :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen:
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