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 to make a MS-DOS C compiler emit a far call with immediate segment and offset into the data segment?
I am trying to recreate the C source code from some 16bit DOS 8086 assembly generated by the MS C 5.0 compiler. I've hit a wall with this far call instruction.
0000008D 9A2F0CB506 call 0x6b5:...
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Did MS-DOS have any support for multithreading?
Common wisdom seems to be that MS-DOS was an exclusively single-threaded OS. Of course, implementing a scheduler would be possible, but the OS itself did not provide any facilities for multithreading, ...
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Math and French practice floppies
A long time ago, at school, they used to provide us with some 5.25 inches floppies each year. The teacher used to boot Unisys PCs with some bootable floppies (I do not believe they had hard disks), we ...
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Basic page layout program from the PrintMaster 2.0 era
I remember it as "Fantasy" but the lack of results makes me think I may be wrong.
All I know for sure is that it was a single page layout program; it was contemporary with PrintMaster 2.0, ...
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How did ‘logically-sectored FAT’ work?
While browsing online materials about the FAT file system, I occasionally came across mentions of ‘logically-sectored FAT’. This was apparently some kind of special mode of formatting a hard drive, ...
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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 ...
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When did Kay Nishi offer a million dollars for a competing DOS?
The development of Digital Research's fully-compatible MS-DOS competitor, DR DOS, was encouraged when, according to https://retrotechnology.com/dri/dri_wein.html
After DOS Plus for Philips we did a ...
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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. ...
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Did Digital Research clean-room MS-DOS?
From https://en.wikipedia.org/wiki/DR-DOS
DR-DOS (written as DR DOS, without a hyphen, in versions up to and including 6.0) is a disk operating system for IBM PC compatibles. Upon its introduction in ...
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Which is the first version of DOS to support more than one reserved sector in a FAT file system?
I'm trying to fix a problem when trying to use DOS stuff on SSDs. The problem is sector alignment in an SSD is completely different from what DOS expects, and writes to FAT do funny things when the ...
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Alternatives for TurboVision on DOS
TurboVision was a library by Borland for developing TUI's (Text User Interfaces). It was included with their C++ and Pascal compilers.
Were there any other TUI libraries that supported multiple ...
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How to use the "darker" CGA palette using x86 Assembly?
For those of you retro developers out there, I am having a hard time figuring out how exactly to select the "darker" color palette in 320x200 CGA mode. Here's what I have so far:
setup_cga_graphics:
...
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Can HIMEM.SYS be disabled in Windows ME’s IO.SYS?
Windows ME's IO.SYS includes HIMEM.SYS, which it loads unconditionally. Since it is possible to decompress and disassemble IO.SYS, and hack it to enable full DOS mode, can we go a step further and ...
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Memory requirements for undelete command
During MS-DOS days, an Undelete command existed and provided three levels of protection. Sentry is pretty much the same as the Recycle Bin, it moves deleted files to a directory called Sentry. Tracker ...
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Disable motherboard floppy controller DOS
I have a SuperMicro P4SCA motherboard (manual) running FreeDOS 1.3. The motherboard has an onboard floppy controller as part of a W83627HG (datasheet). However, this floppy control fails to provide ...
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Tiny libc for DOS 8086
I'm looking for a tiny libc (C runtime library) targeting small model DOS 8086, and providing (most of) the C89 library functions, including fread(...), printf(...) and scanf(...). The libc must work ...
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What type(s) of compressed files was the MS-DOS EXPAND command able to decompress?
What type(s) of compressed files was the MS-DOS EXPAND command able to decompress?
And what command was its counterpart?
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Why was the graphical user interface version of Defrag removed?
I remember in MS-DOS 6.22 that Defrag had a GUI that showed its progress and how it was moving files. It wasn't there in Windows XP and I can only assume that it wasn't in Windows 95, 98, 2000 either (...
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How can I boot or extract files from an IBM PS/1 with a DoubleSpace-compressed hard drive?
I’m trying to boot an old IBM PS/1, mostly with the intention to read out its hard disk. I realized quickly that the original floppy disk drive was broken, so I replaced it with a Gotek floppy ...
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Which font with slashed zero is being used in this screengrab?
Do you know which font is being used in the video here: https://www.youtube.com/watch?v=xnudvJbAgI0? A screengrab of the video that shows a lot of text:
We can see that the zeros are slashed, so it ...
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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 ...
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Why did MS-DOS choose the percent symbol to designate variables?
I couldn't find anything but is there any reason for choosing % over $ like in *nix shells?
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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 ...
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Why did "protected-mode MS-DOS" never happen?
Software written for MS-DOS used DOS extenders as early as on PC/AT (DOS/16M), and starting from i386-based systems, DOS extenders became really widespread.
I'd think it was pretty obvious at the time ...
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When was QDOS changed to MS-DOS?
So a while back, I heard that MS-DOS was originally named QDOS (Quick and Dirty Operating System), and that it was later changed is MS-DOS (Microsoft Disk Operating System). This was probably a ...
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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 ...
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Disk compression risks in MS-DOS
Continuing my nostalgia reading of Dan Gookin's DOS For Dummies, there is a section that literally advises against compression programs like DriveSpace and calls it a solution to a problem not some ...
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Looking for an open source DOS .com program written in assembly
I'm writing a NASM-compatible assembler targeting the Intel 8086, and I'm looking for an existing open source program written in assembly, with which I can showcase the capabilities (and understand ...
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What were the actual memory model definitions in MS-DOS?
I've heard the phrase "memory model" used in relation to MS-DOS programming (and early Windows), with terms such as "small" and "compact".
But what were the actual ...
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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 ...
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Tandy 1000 TDYSPKR utility
I've seen reference to a TDYSPKR (.EXE or .COM?) tool that sets audio output options on the early Tandy 1000 series of computers (1000, 1000A, 1000SX, 1000TX, maybe others). Apparently it can toggle ...
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Running DOS, Windows 3, and Windows 98 from one FAT32 partition?
I'd like to setup a Windows 98 SE system that boots into the included MS-DOS 7.1 command line, and which can also run Windows 3.11. I've seen various disjointed posts online that suggest this is ...
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What was this menu application in DOS?
My father's computer in the early 90s (probably 1991, or at the latest 1992) had a piece of software that acted as an application launcher. I think it was simply called "menu".
Its graphics ...
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VisiCalc V1.0 is not working on modern computer as expected
I am trying to run Visicalc on the modern laptop (Lenovo Thinkpad X1 Extreme Gen.2). I created bootable flash drives with DOS 6.22 and Free DOS, booted from them and ran visicalc (vc.com file).
All ...
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How to use all memory on an IBM PC with 8086
I'm developing software for the IBM PC with an 8086 processor. I want my program to use all available memory.
I know that I can use DOS int 21h function AH=48h to allocate all available conventional ...
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MS DOS 6.22 hangs on modern hardware after loading HIMEM.SYS
I am trying to run MS-DOS 6.22 on modern hardware. I successfully created bootable flash disk with MS-DOS 6.22. But when it starts with HIMEM.SYS enabled in CONFIG.SYS it hangs. Searching Internet the ...
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MS-DOS Bear/Teddy Bear Spooky Halloween game?
In about 1993-4 I played a (probably free or shareware) MS-DOS game about a bear/teddy bear entering a house which was "spooky", I believe related to Halloween. Graphically it was primitive, ...
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Purpose of Recover command in MS-DOS
Continuing my reading of Dan Gookin's MS-DOS 6 pour les nuls (More DOS for Dummies ?), I've discovered in an otherwise light and funny (at least the French translation is) book about DOS a section ...
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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 ...
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How did SmartDrive work?
I've recently unearthed an old book called MS-DOS 6 pour les nuls (More DOS for Dummies) by famed C programmer Dan Gookin. It was (still to me) a very interesting book in which he talks about MS-DOS ...
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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, ...
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What versions of MS-DOS or PC-DOS supported the "+,," syntax on COPY? Is there documentation on its origin?
I remember reading in an IBM PC-DOS manual, around 1988 maybe, that there was a special syntax of the COPY command :
COPY A.TXT +,,
which would simply update the file's last change date to now. This ...
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How much of the Program Segment Prefix area can be reused by programs with impunity?
I am writing a tiny TSR program, and I want it to take as little memory while installed as possible. The memory footprint of every loaded DOS process, including a TSR, includes a data structure known ...
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What was the purpose of the ‘overlay number’ field in the MZ executable format?
Many materials covering the layout of MZ executables (RBIL, for example, and even a comment in MS-DOS 2.0 source code) describe the word at offset +0x1a as the ‘overlay number’, with the value zero ...
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Does the kernel of Windows 95/98/ME have a name?
In this question:
Why was the DOS kernel discarded?
I was told that DOS is not a kernel. It runs on CPUs that don't even have kernel mode. So how can it be a kernel? So I think this is right.
Now if ...
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How can I properly execute and clean up after a DOS MZ executable loaded into memory with int21 function 4b01h?
Ralf Brown's Interrupt List describes a subvariant of the DOS int21/4Bh function with AL=01, where the program is loaded into memory and a PSP + stack are allocated for it, but the program is not ...
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Why was the DOS kernel discarded?
I've read that the last DOS kernel based Windows was ME. Later versions use the NT kernel.
Why did Microsoft rewrite the whole kernel? Why was the DOS kernel discarded?
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Origin of PALMPC.ZIP "Palm PC emulator"
The program PALMPC.COM, which is available on an old link in the Internet Archive, and also on e.g. S.U.P.E.R., apparently provides graphics emulation, including interrupt 0x5F used by the HP/Lotus ...
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What are these compression types in the ARC file format?
The file format of the SEA ARC compression tool, also used by the PKWare PKARC tool, allowed the following compression types:
Packing (RLE encoding)
Squeezing (static Huffman coding)
Crunching (LZW)...
CommunityBot
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Why have MS-DOS device drivers if the ROM BIOS provides access to the same devices already?
IO.SYS is an essential part of MS-DOS that contains the default MS-DOS device drivers.
IBMBIO.COM is a system file in PC-DOS. It contains the built-in device drivers.
Based on the answers of the ...
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