Questions tagged [bios]

To be used when asking questions about the Basic Input/Output System found on many computers.

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62
votes
8answers
15k views

Why did IBM make the PC BIOS source code public?

IBM released the IBM 5150 Technical Reference manual in August, 1981, and included in it the fully commented source code listing for the BIOS. I find this odd for two reasons: IBM must have realized ...
16
votes
4answers
1k views

Did the IBM PC use the 8088's NMI line?

As I understand it, the Intel 8088 CPU used in the original IBM PC had two interrupt lines: INTR and NMI. INTR was fed from the Intel 8259 Programmable Interrupt Controller, which handled the IRQs ...
29
votes
9answers
9k views

How did early x86 BIOS programmers manage to program full blown TUIs given very few bytes of ROM/EPROM?

I've always wondered how so much functionality and relative luxuries(CMOS Configuration Utilities. See: https://geekprank.com/bios/ for an example) included with most popular x86 BIOSes could be ...
6
votes
1answer
321 views

What's the fastest way to ignore keypresses?

I'm writing a game for the IBM PC (running MS-DOS), complete with fancy cutscenes. Unfortunately, though, the keys pressed during those fancy cutscenes are carried out once the fancy cutscene has ...
-1
votes
2answers
302 views

Why can't BIOS be accessed in 64bit mode on Intel/AMD chips? [closed]

I was interested in a possible rewrite of dos to dos 64bit. In my research I found several references that state all current motherboard BIOS interrupts are not accessible from 64bit Long or 64bit ...
1
vote
2answers
270 views

Can DOS 6.22 recognize more than 504MB when the BIOS only supports CHS?

My CMOS setup correctly recognizes the geometry of the drive, (but does not support LBA). And FDISK in DOS 6.22 only recognizes 504MB. FDISK even shows the size of the primary partition as roughly ...
0
votes
2answers
359 views

Does anyone have an x86 EGA draw pixel routine?

So far, I have gotten by with using the BIOS draw-pixel routine here: http://stanislavs.org/helppc/int_10-c.html This works of course, but I can't imagine that commercial games used this BIOS call as ...
4
votes
2answers
462 views

Starting a multi core CPU as single core [closed]

Is it possible to use a system with a modern, multi-core CPU with older operating systems that only support single core operation? Is this something that needs to be set in the BIOS? Does it depend ...
6
votes
1answer
416 views

How can I edit CMOS hard drive geometry settings on a 1991 PC?

First, I am NOT asking how to use the BIOS Setup utility. I'm asking how to OVERRIDE the built-in settings my BIOS Setup supports for the HD geometry. I have a 1991 NCR PC with a 386SX, on-board IDE, ...
1
vote
1answer
179 views

Support for 5.25-inch floppy drives on IBM Thinkcentre 8187 KUR

I have an IBM ThinkCentre 8187KUR desktop system. It has a bay for 5.25-inch floppies but no support in the BIOS. My question is, can I put in a PCI card to support floppy drive access and run the 5....
9
votes
1answer
1k views

What happens when PS1's “Fearful Harmony” is triggered?

When inserting an incompatible disc into a Playstation, after waiting awhile the screen will display very corrupt graphics and unsettling music will begin to play. This is unofficially referred to as "...
3
votes
1answer
307 views

XT-IDE Universal BIOS does not find master drive on XT CF Lite card

I have built a XT CF Lite v4.1 to boot my 286 with a compact flash card. I have configured it via DIP switches to address 300h and I am using the XT-IDE Universal BIOS 2.0.0 beta 3. This is I think ...
8
votes
1answer
274 views

How did Drive Overlay programs break BIOS disk barriers on older PCs?

I was just reading a thread on Vogons about OnTrack and EZ-Drive setup, and it occurred to me that I have no idea how they work. Please explain why the barrier existed and then how the overlay ...
7
votes
4answers
896 views

How did DOS know where to load itself in upper memory?

If I remember correctly, you could ask DOS to load in upper memory by writing something like... DOS=UMB ...somewhere in the CONFIG.SYS file. But the question is, how did DOS know what portions of ...
6
votes
2answers
668 views

Who were the first engineers to “cleanroom” the IBM PC BIOS?

In the first season of the AMC show Halt & Catch Fire, the protagonist "Cameron Howe" is introduced. Cameron portrays a rookie engineer who is recruited for being extraordinarily talented, and is ...
8
votes
1answer
368 views

Can the system's BIOS come from an ISA card?

If an ISA card was configured to respond to the address range of the system's BIOS (and the BIOS chips removed), could you boot from it in the same way as the system's default BIOS? Specifically, I'm ...
4
votes
2answers
241 views

How to debug BIOS ROM incompatibility?

I'd like to use the XT-IDE Universal BIOS with an IBM XT 286 (5162), but it's known to be incompatible. With the card installed, it will not boot from a floppy from which it would otherwise boot (it ...