Questions tagged [ms-dos]

MS-DOS, the Microsoft Disk Operating System, its OEM-branded versions, and x86 DOS clones in general.

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How did Windows 3.1 implement multitasking?

Windows in its earliest days was simply a shell that ran on top of MS-DOS, which means that Windows 3.1 itself was actually just a standard MS-DOS application like any other. Yet, MS-DOS is not a ...
Mike Nielsen's user avatar
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78 votes
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Why is Windows using CR+LF and Unix just LF when Unix is the older system?

Windows and MS-DOS use the control characters CR+LF (carriage return ASCII 13 followed by line feed ASCII 10) for new lines, while Unix uses just LF. As far as I know CR+LF made sense for systems ...
allo's user avatar
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72 votes
3 answers
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Why did DOS use dollar-terminated strings?

According to a few tutorials I am seeing, DOS used dollar-terminated strings to write to the terminal. This seems to also be documented here on INT 21H. AH = 09h - WRITE STRING TO STANDARD OUTPUT ...
Evan Carroll's user avatar
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69 votes
3 answers
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What character is the MS-DOS cursor?

The cursor used on my 486 (and Pentium 3) in MS-DOS 6/7 has a thick underlined character. I cannot find that in code page 437. The underscore character is the closest to it, but is thinner. Where ...
Thraka's user avatar
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63 votes
7 answers
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Why did the MS-DOS API choose software interrupts for its interface?

Access to the DOS API was done through the INT 21h x86 instruction. This was always counter-intuitive to me, coming from 8-bit systems that accessed system services by calling subroutines through a ...
Brian H's user avatar
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62 votes
7 answers
10k views

Why did some old MS-DOS games lack the ability to exit them?

While playing around in DOSBox-X, I'm reminded of some DOS games which appear to entirely lack the ability to exit/quit/close them. One prime example of that is "Paratrooper" from 1982. I've ...
Kenas's user avatar
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50 votes
1 answer
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What is the context of the button "Is MS DOS a feminist?"

I just saw this button in the Computer History Museum, and I'm wondering what is the context? Context removed, "Is MS DOS a feminist?" is about the most non-sequitur thing I've seen.
Evan Carroll's user avatar
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49 votes
9 answers
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Why weren't bootable game disks ever common on the IBM PC?

While for other platforms of that era (primarily, Amiga), putting a game on a bootable disk was quite a normal practice, this approach never taken off on IBM PC. Why not? I do remember people having ...
DmytroL's user avatar
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46 votes
2 answers
8k views

Did IBM encourage Bill Gates to retain the rights over PC-DOS?

As is well-known, Microsoft's negotiations with IBM to deliver PC-DOS 1.0 with the original IBM PC resulted in: IBM licensing the OS from Microsoft, as opposed to purchasing it outright. Microsoft ...
Brian H's user avatar
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44 votes
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Is DOS being shipped with or as an installed OS?

Given the very small size of DOS, it would seem it might still be ideal for some applications such as handheld games. Is any system manufacturer still shipping DOS with their machine? If no one is ...
Barnstormer's user avatar
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42 votes
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How do DOS games like DOOM benefit from a PCI graphics card?

The original DOOM and its derivatives (DOOM II, Heretic, Hexen) were early 90s 3D games released at a time when DOS PCs usually had ISA bus Super VGA graphics cards. In the following few years, PCs ...
Brian H's user avatar
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41 votes
2 answers
7k views

How did Windows ME "cripple" DOS?

Windows ME includes the ability to create a bootable DOS floppy. This floppy contains versions of COMMAND.COM and IO.SYS that are "crippled" to remove real mode. This is done with only one changed ...
wizzwizz4's user avatar
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41 votes
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Where and what was Haunt.bat? A game pre-loaded on a c1992 PC

This doesn't belong on the gaming SE, so I'm trying my luck here. I'm looking for any info I can get on an old game that I simply known as "Haunt.bat". Here is the back-story: In the mid 90's a ...
Gorchestopher H's user avatar
39 votes
2 answers
4k views

Do any FAT8 filesystem images survive?

According to Wikipedia, the original FAT8 filesystem was developed by Marc McDonald in 1977 or 1978, as part of "NCR BASIC +6", a port of Microsoft BASIC to an 8080-based NCR data entry ...
Simon Kissane's user avatar
37 votes
3 answers
3k views

How can I play QBasic Nibbles on a modern machine?

MS-DOS versions 5 and 6 come bundled with the QBasic interpreter and a handful of example programs written in that BASIC dialect. One of the programs is Nibbles, a variant of the well-known Snake game....
user3840170's user avatar
37 votes
2 answers
8k views

Why does Windows 1.01 crash at the splash screen?

When Windows 1.01 is started under DOSBox, FreeDOS or one of the later versions of MS-DOS, garbage characters are printed on the screen right after displaying the Microsoft logo. Here’s an example in ...
user3840170's user avatar
36 votes
6 answers
13k views

Is there a simple way to display ANSI art and animation files in a modern terminal window?

ANSI art and animations were prevalent on BBS systems in the late 80s and early 90s, and the ANSI art scene continues to thrive today. There are thousands of ANSI art files, with usual extension .ans, ...
Brian H's user avatar
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35 votes
10 answers
9k views

Is there a reason to prefer earlier versions of MS-DOS over later?

I understand MS-DOS to be backwards-compatible, so is there a reason to run a version earlier than the last (6.22) on an old computer? The only reason I can think of would be for period-accuracy, but ...
Sydius's user avatar
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35 votes
3 answers
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Why did DOS-based Windows require HIMEM.SYS to boot?

My understanding is that all versions of Microsoft Windows that ran on top of DOS — that is, the lineage from Windows 1.0 up to Windows ME, even though the reliance on DOS diminished over time — ...
mkay's user avatar
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34 votes
8 answers
7k views

How to put a delay in AUTOEXEC.BAT

I have this MS-DOS 6.22 machine which maps a network drive to a SAMBA share on a Raspberry PI. The PI is powered by a USB lead from the DOS machine, so the two power up together. The mapping starts ...
Rodney's user avatar
  • 503
34 votes
4 answers
6k views

Why was 'echo on' chosen as the default setting within batch scripts in MS-DOS?

In my experience, just about every single MS-DOS (and thus Windows cmd) batch file starts with the line @echo off, to silently switch off echoing of the commands in the batch file to the console. This ...
hBy2Py's user avatar
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34 votes
2 answers
5k views

How did MS-DOS assign drive letters in the case of more than two floppy disk drives?

The IBM PC BIOS had provisions for up to four floppy disk drives, by virtue of returning the number of floppy disk drives in a two-bit field plus a none/some flag (allowing for reporting values of 0, ...
user's user avatar
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33 votes
1 answer
3k views

How does the command.com shell work with MS-DOS?

On my systems that are running MS-DOS, I change the default command.com to 4DOS for more features. How was the shell system designed and how did it with the operating system in MS-DOS that it enabled ...
Thraka's user avatar
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32 votes
6 answers
7k views

Why did the monsters have "infinite invisible pillars" of hitboxes vertically in all versions of the DOOM engine?

Even in the last version of the DOOM engine, v1.9, used for Final DOOM, there is this strange limitation in which all the monsters have an invisible, infinitely tall "pillar" above and ...
Farrad's user avatar
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32 votes
1 answer
3k views

Did DOS zero out the BSS area when it loaded a program?

As an example, say we have a DOS MZ EXE file that's around 20 KiB in size. The EXE header contains the value 0x1400 at offset 0x0A indicating that the program is requesting 5,120 paragraphs (or 80 KiB)...
smitelli's user avatar
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31 votes
3 answers
8k views

Were 9.2 file names possible in MS-DOS?

In MS-DOS (and FAT16), you could only have 8.3 file names (like QUESTION.TXT) with only single-case letters and numbers (and a few symbols). The MS-DOS Editor also defaulted to 8.3 - typing edit ...
Zackary's user avatar
  • 605
31 votes
3 answers
6k views

Why was the DOS clock device renamed from CLOCK into CLOCK$?

From the Wikipedia article on reserved device names ... and the CLOCK$ (still named CLOCK in some issues of MS-DOS 2.11) clock device were introduced with DOS 2.0, ... Why was is necessary to add a $...
Sep Roland's user avatar
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31 votes
5 answers
5k views

What really is a sound card driver in MS-DOS?

To my knowledge, neither MS-DOS nor BIOS offers any kind of API for sound cards. Therefore the concept of a "driver" is absent, as we know it today. Apart from accessories and sample files ...
Dercsár's user avatar
  • 675
31 votes
2 answers
5k views

Did any MS-DOS program ever use the System Request interrupt?

As I remember, the SysRq key generated a special, unique interrupt (not an ordinary keyboard interrupt). It was supposed to let the user interrupt any process in a multitasking situation and return ...
Miss_Understands's user avatar
30 votes
3 answers
4k views

What exactly did the "UNFORMAT" MS-DOS command do?

I found only this: The UNFORMAT command is used to undo the effects of formatting a disk. The command is available in MS-DOS versions 5 and later. Source: https://en.wikipedia.org/wiki/...
P. Molet's user avatar
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29 votes
5 answers
9k views

Are MS-DOS and Windows 9x vulnerable to Meltdown?

In an interesting crossover between current events and Retrocomputing, the vulnerability known as "Meltdown" was publicly disclosed on January 3rd 2018. The retro-computing tie-in is that this ...
Brian H's user avatar
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29 votes
1 answer
5k views

Did the original MS-DOS Quake not have a menu item for freelook, and if so, why?

I know that Quake (the 1996 MS-DOS game) is a "full" 3D engine, and always had some kind of mouse support. However, even the original Wolfenstein 3D from 1992 also had mouse support from the ...
Faisal's user avatar
  • 307
28 votes
4 answers
5k views

What's the relationship betweeen MS-DOS and XENIX?

Browsing MS-DOS sources on GitHub, I often see mentions of XENIX: DOSSYM.ASM: ; XENIX calls all return error codes through AX. If an error occurred then the ; carry bit will be set and the ...
Igor Skochinsky's user avatar
28 votes
5 answers
7k views

Why are Windows 95 installation disks not uniquely bound to a single product key?

I was installing the OEM version of Windows 95 on VirtualBox the other day for reminiscence sake, and for some reason I had two different product keys. I tested both of them to see which one mapped to ...
Retro Gamer's user avatar
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28 votes
2 answers
12k views

Looking for PC graphics demo software from the early 90s called "Unreal"

Back in the early 90's I remember downloading a graphics demo called, I think, "Unreal". This was on DOS on a standard PC and probably downloaded from a BBS. Identifying information: It ran for ...
StayOnTarget's user avatar
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28 votes
5 answers
3k views

Why does the FAT file system have separate ‘hidden’ and ‘system’ attributes?

File systems used by DOS and Windows have used file attribute bits as a relatively prominent feature. The first of them, FAT, exposes four attributes to the user: read-only, archive, hidden and ...
user3840170's user avatar
27 votes
4 answers
4k views

Why wasn't DOSKEY integrated with COMMAND.COM?

Why did Microsoft make DOSKEY a separate command, instead of integrating it with COMMAND.COM? I don't think DOSKEY uses a lot of RAM or was useless in the '80s... Maybe there was another reason not ...
user7710's user avatar
  • 583
27 votes
9 answers
8k views

What other tricks were there to get more data onto floppy disks?

I remember using a utility back in MS-DOS 3.3 days, called MAXI Disk, that somehow magically managed to get 420K on a 360K 5¼″ disk. I assume it managed it by destroying some redundancy like a backup ...
user230910's user avatar
27 votes
3 answers
4k views

Most modern C compilers targeting DOS 8086, running on DOS 8086 (16-bit)

I'm looking for the most recent versions of modern C compilers which were/are targeting DOS 8086, also running on DOS 8086 (16-bit). I'm mostly interested in production-ready C compilers, rather than ...
pts's user avatar
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27 votes
2 answers
4k views

Did MS-DOS ever drop ability to support non-IBM PC compatible machines?

Early MS-DOS versions were designed and indeed adapted to run on machines not fully IBM PC compatible. However, there seems to be a number of utilities bundled with later versions, that seem not to ...
tuomas's user avatar
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26 votes
3 answers
14k views

Why was "C:" chosen for the first hard drive partition?

I was reading this answer, as the question came to my mind: why does C: indicate the first hard drive partition? The usage dates back to CP/M (as noted in a comment), was embraced by MS-DOS, and ...
wizclown's user avatar
  • 403
26 votes
3 answers
7k views

Why does DOS ask for the current date and time upon booting?

In most versions of DOS, when they are started from a medium that lacks an AUTOEXEC.BAT file, the very first thing COMMAND.COM does is ask the user to confirm the current date and time: Starting PC ...
user3840170's user avatar
26 votes
3 answers
5k views

Where did DOS store graphics fonts?

I remember using a wysiwyg print program called Fontasy for CGI graphics in DOS because of a lack of standardized graphics fonts. Companies were selling "font packs" for other type fonts. Prior to Win ...
Barnstormer's user avatar
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26 votes
7 answers
6k views

How did DOS games manage to have multiple background layers?

Seems like VGA only has one background layer, it appears to be a typical bitmap screen like most home computers of the 80s (Amstrad CPC, Commodore 64 etc.) where each pixel's color is stored in a ...
puppydrum64's user avatar
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26 votes
3 answers
7k views

Why might Quake run slowly on a modern PC in DOS, but not in a virtual machine?

I noticed back in the DOS gaming era that DOS games ran slowly in hi-res modes. I was surprised to discover that this could be true on a modern machine. I booted a 2017 i5 7200u (I think) laptop into ...
Leon Simpson's user avatar
26 votes
3 answers
4k views

What did Ctrl+NumLock do?

In my answer here I infer that the unusual scancode for the Pause/Break key emulates the user pressing and then releasing CtrlNumLock. Obviously that key combination did something specific, back when ...
user253751's user avatar
25 votes
12 answers
5k views

Why did CP/M and MS-DOS use the BIOS instead of their own drivers to access hardware?

Modern versions of Windows (and other modern operating systems I suppose) have their own drivers to access hardware. But as I have read, in the old days, if CP/M or MS-DOS wanted to access hardware, ...
user7681202's user avatar
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25 votes
3 answers
5k views

Did MS-DOS itself ever use blinking text?

I know that it was possible to create blinking text, but did the operating system itself (I mean, in output from functions of COMMAND.COM and similar executables) ever make use of blink formatting? ...
KlaymenDK's user avatar
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25 votes
2 answers
4k views

Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded?

Quoting from Jim Hall's "FreeDOS turns 25 years old: An origin story": Around 1994, Microsoft announced that its next planned version of Windows would do away with MS-DOS. But I liked DOS. ...
ArrayBolt3's user avatar
25 votes
1 answer
4k views

What is 'Adaptive Tile Refresh' in the context of Commander Keen?

The question Did John Carmack really invent "Adaptive Tile Refresh"? asks about the origins of the scrolling and drawing techniques used to allow an MS-DOS PC to provide a NES console-like ...
knol's user avatar
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