• Please review our updated Terms and Rules here

XTIDE Universal BIOS v2.0.0 beta testing thread

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).
 
Last edited:
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
 
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 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
 
Last edited:
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.
 
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.)
 
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.
 
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".
 
Indeed. It might be pointless now though - I don't think there will be that many more revisions.
Well, you never know what's around the corner, Maybe one day the XUB can support the ISA - USB controller.
 
@ajacocks
It's just that the BIOS is more or less finished. I might do minor changes but anything more time consuming (adding additional controller types, like the ISA USB controller for example) probably won't happen, at least not in the near future. I've been meaning to add some simple ATAPI device detection and I can't even find the time to do that.
 
I'm sure there will still be additions for supporting the various ISA USB projects floating around, although hopefully those will be pull requests and not more work on your part :)

There was a feature or features I wanted to add to the XUB, which is why I inquired about building it myself a few months back, but unfortunately I've forgotten what it was I wanted to add :-(
 
Back
Top