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14 votes
Accepted

Detecting if a video mode is supported by INT 0x10

Indeed, in many sources, the int10h subfunction AH=0 to set video mode returns without any meaningful status. One way, suggested by C&T BIOS programming guide, is to verify if the mode is set via ...
Justme's user avatar
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13 votes

Detecting if a video mode is supported by INT 0x10

That's not how you designed your programs in the early days of the PC: You rather decided for one (maybe two) video cards (typically CGA and/or Hercules Monochrome) and then looked up your ...
tofro's user avatar
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13 votes
Accepted

Can someone explain the logic behind Pause and Print Screen modifiers?

Take a look at the pictures in the Wikipedia article on IBM PC keyboard. On the original 83-key keyboard: The PrtScr function is Shift and PrtScr *, used to print what is currently on the screen. In ...
Bavi_H's user avatar
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9 votes

Can someone explain the logic behind Pause and Print Screen modifiers?

It depends on which era keyboard you have. Not all keyboards have the same buttons and they don't work identically. And every time there was some changes and key functions were combined or shuffled ...
Justme's user avatar
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8 votes

Detecting if a video mode is supported by INT 0x10

BIOS has the ReturnFunctionalityStateInformation function 1Bh that can be used to retrieve a 20-bit bitmap of the supported video modes. You supply a far pointer to a 64-byte buffer that BIOS will ...
Sep Roland's user avatar
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8 votes

Rufus FreeDOS option for CF is not bootable

Since you can't boot a FreeDOS install floppy on the target machine, you can make a disk image, and mount/use it with identical geometry in a virtual machine, and then install the OS in the virtual ...
Justme's user avatar
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4 votes

Detecting if a video mode is supported by INT 0x10

There's a big list of video modes available, but how can I be sure that the video mode I want to set is supported? There is no easy way - unless you can determinate what kind of Card it is. For new ...
Raffzahn's user avatar
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2 votes
Accepted

Rufus FreeDOS option for CF is not bootable

For those who are interested, there is another way to solve this problem: use 86Box (x86 Emulation), add a harddrive and set it to a maximum of 504MB (PreSet selection), insert the boot image of ...
leon22's user avatar
  • 354
2 votes

Why did "protected-mode MS-DOS" never happen?

I'd think it was pretty obvious at the time that the real-mode limitations of both BIOS and MS-DOS Real-mode limitations are not of BIOS or MS-DOS. Real-mode uses a 16bit addressing + segmentation, ...
stsp's user avatar
  • 161
1 vote
Accepted

Have I Screwed the CMOS by Booting With the Clear Jumper Set?

No, I'm just an idiot who didn't go back and check his assumptions. Maybe this will happen to somebody else, hopefully not. In the end I ordered a spare motherboard off eBay (relatively cheap, so not ...
Matt Lacey's user avatar
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