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XTIDE Universal BIOS v2.0.0 beta testing thread

dmac

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May 18, 2020
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I wrote a free (MIT) tool, optromloader, to load Option ROMs into conventional memory from a floppy. Great for trying out XTIDE Universal BIOS without burning ROMs.

It should work on any PC/XT/AT or clone. I've tried a bunch on PCem. Of course it also works on the real hardware I wrote it for (486DX2 on AMI BIOS board).
 
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Krille

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dmac The stack changing should be done with interrupts disabled to avoid problems with old buggy 8088/8086 CPU:s.

Like this;
Code:
cli
mov ss,ax ;handed-over SS could be anything, like CS
mov sp,$7C00 ;set a stack right under the bootloader
sti
 

Krille

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not big deal but when I look at diagnostic programs like NSSI then in BIOS summarization header of XTIDE is missed. Not found / unknown.

When looking at the version history for that program it seems the author added detection for specific BIOSes which makes sense as there isn't really a standardized way to do that. I'm afraid there's nothing I can do about it.
 

dmac

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May 18, 2020
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dmac The stack changing should be done with interrupts disabled to avoid problems with old buggy 8088/8086 CPU:s.
Like this;
Code:
cli
mov ss,ax ;handed-over SS could be anything, like CS
mov sp,$7C00 ;set a stack right under the bootloader
sti

Possibly. Do you have a source about these bugged versions? I tried some searches without success.

What I read is that if SP is set right after setting SS, the CPUs have special handling which prevent interrupts on the immediate instruction after setting SS, thus it can't happen.

https://wiki.osdev.org/My_Bootloader...ately_after_SS
 
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dmac

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May 18, 2020
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not big deal but when I look at diagnostic programs like NSSI then in BIOS summarization header of XTIDE is missed. Not found / unknown.

I suspect that, like BIOSs, they only scan upper memory for Option ROMs, not conventional memory.
 

Krille

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Possibly. Do you have a source about these bugged versions? I tried some searches without success.

It's a well known bug and it has been discussed here on the forum in the past. It's mentioned in RBIL in 86BUGS.LST. See the part about MOV here. (I'm pretty sure it applies to POP as well even though it isn't mentioned in the section about the POP instruction.)
 

dmac

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May 18, 2020
Messages
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It's a well known bug and it has been discussed here on the forum in the past. It's mentioned in RBIL in 86BUGS.LST. See the part about MOV here. (I'm pretty sure it applies to POP as well even though it isn't mentioned in the section about the POP instruction.)

Taken care of this. Thank you.
 

Malc

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When looking at the version history for that program it seems the author added detection for specific BIOSes which makes sense as there isn't really a standardized way to do that. I'm afraid there's nothing I can do about it.

I suspect some look for copyright signatures (C) COPR. COPYRIGHT in the bios, I just tested this using an old infoplus utility, I did a custom build of XUB and added " (C) " in the code, Before adding the (C) infoplus reported the XUB ROM as " Unknown ", After the mod infoplus reported the XUB ROM as
"(C) XTIDE Universal BIOS".
 
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