Setting Up a dual boot rom

Upgrade or replace the ROM.
Glorfindeal
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Setting Up a dual boot rom

Post by Glorfindeal »

I’m looking at doing my own dual boot rom with Exxos STe dual TOS kit.
First off, what part number eprom do I need to buy?
Second, with 2 TOS roms files, how do I join them to burn to the eprom? (Also, where can I get a 16 bit 1.62 rom file?)
Third, will this eprom programmer work:
PRG-113 True USB Willem GQ Brand GQ-4X V4 (GQ-4X4) USB Universal 40 pin Programmer with 16 bit adapter.

Since I have never used a eprom programmer, any help would be appreciated.

Thanks,

Ken
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derkom
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Re: Setting Up a dual boot rom

Post by derkom »

Glorfindeal wrote: Sat May 09, 2020 2:25 pm First off, what part number eprom do I need to buy?
Atmel AT27C4096.
Second, with 2 TOS roms files, how do I join them to burn to the eprom? (Also, where can I get a 16 bit 1.62 rom file?)
I've used CartMan, which requires a Windows machine/emulator.

You can find all the TOS ROMs here.
Third, will this eprom programmer work:
PRG-113 True USB Willem GQ Brand GQ-4X V4 (GQ-4X4) USB Universal 40 pin Programmer with 16 bit adapter.
Looks fine, as long as you have the correct adapter for the 27C4096 chip.

Don't make the mistake I made when trying this the first time. I ended up with a byteswapped TOS, which obviously won't boot. Follow @PhilC's advice here and find a text section in the rom file after you load it in your programmer software and make sure it's readable. If it's byteswapped, CartMan can fix that for you.
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PaulJ
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Re: Setting Up a dual boot rom

Post by PaulJ »

derkom wrote: Sat May 09, 2020 3:05 pm
Glorfindeal wrote: Sat May 09, 2020 2:25 pm First off, what part number eprom do I need to buy?
find a text section in the rom file after you load it in your programmer software and make sure it's readable. If it's byteswapped, CartMan can fix that for you.
Couple of things.. you really don't need a special app to combine images. Load a image into a hex editor. If its length is not 0x40000 pad it out so it ends at 0x3FFFF. Append your second rom image on top... ie: start at 0x40000. If its not a 256k but a 192k pad it out to 0x7ffff. Funny thing though, all the boot images I make for Exxos's hardware require both images have the text NOT readable. If you can read the imbedded text prior to burning it won't work. After stacking the two images the text should be the same in both half.. not readable or readable. If you can read the text you have to byte swap the image. My programmer app does that. Also as a point of byte order my eprom emulator requires the bytes to be swapped if the text is readable. @PhilC you should take one of your eprom that work, read it out in the eprom programmer and examine it with a hex editor. I believe you will find that the text is not readable. If you examine the rom area on the Atari the text will be readable if the burned image is swapped.
Glorfindeal
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Re: Setting Up a dual boot rom

Post by Glorfindeal »

Luckily the 16 bit adapter does support the 27C4096 chip.


Ken
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PhilC
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Re: Setting Up a dual boot rom

Post by PhilC »

@PaulJ it changes depending on which software I use, one the text is correct, my new eprom programmer its byte swapped. Just have to get used to the order.
If it ain't broke, test it to Destruction.
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PaulJ
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Re: Setting Up a dual boot rom

Post by PaulJ »

PhilC wrote: Sat May 09, 2020 5:17 pm @PaulJ it changes depending on which software I use, one the text is correct, my new eprom programmer its byte swapped. Just have to get used to the order.
Never the less @PhilC you can't claim if you can read it in a hex dump its fine. For example if its @cmorley's eprom simulator or the burner i am using (eetoools chipmax2) burning a image with readable test will result in a slug or nonfunctional eprom.

For example here is a extraction from EMUTOS 1.92 256k.
im1.png
im1.png (27.78 KiB) Viewed 5622 times
If I burn this image into a eprom or the eprom simulator it will be a dud. Not functional in either case or with my old eprom burner. For the rom to work I need to swap the bytes. So you can't tell what's right by looking at it and if you make that statement some of the people will be burning coasters, slugs etc.

So if your unsure which is correct you should test for the proper byte orientation by using a uv erasable eprom so if you get it wrong you swap the bytes and try again without burning a coaster.
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PhilC
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Re: Setting Up a dual boot rom

Post by PhilC »

@PaulJ when using the TL866 and the specific software that comes with it I actually can claim that if you can read the text then the file is fine to burn to a 27c4096 for the Atari.

As also said, itsnot the same with my GQ 4x4 as the file will need to be byte swapped.

Not trying to prove the point, it's as it is with these two specific controllers. Of course I dont know what the original poster has as an eprom programmer and as I'm sure you're aware, I wasnt the one who initially linked to my previous post.

Hope that clears it up.
If it ain't broke, test it to Destruction.
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PaulJ
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Re: Setting Up a dual boot rom

Post by PaulJ »

@PhilC , all true. I guess everyone needs to check how their burner reads the file. In the old days what you saw was what you got. In the trues form you statement should be right but little indian stuff screws it up. I wonder if there's a setting in the eprom burner app that defines how it interprets works. Never the less let the user beware. :)
Glorfindeal
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Re: Setting Up a dual boot rom

Post by Glorfindeal »

Ok, I used the hex editor and both rom files were the correct length. I combined the files and saved them as a combined image file. I'm going to use the GQ 4x4 also. In the hex editor the text was readable. Now how do I byte swap in a hex editor?
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PhilC
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Re: Setting Up a dual boot rom

Post by PhilC »

Glorfindeal wrote: Sat May 09, 2020 8:46 pm Ok, I used the hex editor and both rom files were the correct length. I combined the files and saved them as a combined image file. I'm going to use the GQ 4x4 also. In the hex editor the text was readable. Now how do I byte swap in a hex editor?
Ok, so presuming it's the same as mine, when viewing the buffer press the A=B button at the top, this should byte swap the roms.
If it ain't broke, test it to Destruction.
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