Questions tagged [file-format]

Relating to the encoding format of data within files.

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2
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2answers
273 views

How can I extract game data from Nitemare 3D files?

I am trying to reverse engineer an old Wolf3D style Dos game named "Nitemare 3D". I can get a raycasting engine with directional sprites running pretty easily using SDL2, but I have no experience with ...
12
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2answers
803 views

IBM mainframe classic executable file formats

Most modern platforms have pretty well-defined file formats; e.g. Windows uses PE, Linux and BSD - ELF (previously a.out), macOS - Mach-O, AIX - XCOFF and so on. What were (are?) common executable ...
21
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5answers
5k views

How well known and how commonly used was Huffman coding in 1979?

Infocom's Z-Machine, designed in 1979, compresses text using a basic 5 bit code which is not very efficient in practice, achieving maybe a 1.5:1 compression ratio. Huffman coding would be far more ...
2
votes
2answers
209 views

What was the format for .OBJ files produced by M80.COM for CP/M?

When DOS released in 1981, the assembler that came with it produced .OBJ files that were OMF format. However there was a predecessor to it, M80.COM that ran under CP/M and also used .OBJ as the file ...
7
votes
1answer
262 views

What are the best file formats for backup & emulation of retro game CDs? And why?

In other words, what are some factual, non-subjective reasons why you might choose (or avoid) a certain file format ? (For example, disk usage, audio accuracy, emulator compatibility, etc). I'm ...
5
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3answers
208 views

Opening or converting GFA Basic files to something readable?

There is a bunch of GFA BASIC for Amiga files (the source code for Blender's ancestor, Traces, downloadable here: http://zgodzinski.com/blender-prehistory/) that I would like to peek at. Despite my ...
5
votes
3answers
355 views

How can I debug a Mac OS Classic application?

I have a Mac OS Classic application (a game) that I want to "debug". It has data files in a unique format than I am attempting to reverse-engineer. I've made some progress with a hex editor, but ...
10
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2answers
558 views

Origin of “tarball”

It seems to be common (at least among my section of the world's *NIX users) to refer to "tape archives" made with GNU tar or similar as "tarballs". I always thought this was a slightly odd choice, ...
15
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5answers
3k views

What determines which architecture an a.out executable runs on?

The ELF file format has an e_machine field in the header, which specifies which ISA the executable expects. And the e_ident structure also has an EI_OSABI field that specifies which ABI the executable ...
9
votes
1answer
347 views

How to open a CorelDraw WI wavelet-compressed image

I have a large sample of .WI images I need to convert to e.g. JPEGs, but the format now seems defunct. The mimetype is image/wavelet. The compression algorithm was developed by Summus, a US company ...
26
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3answers
4k views

Magnetic exposure to floppy disk damages file system and requires complete reformat?

What I noticed is, that formatting a floppy disk takes three times as much time for the same data amount as writing a file to the disk normally. The accoustically perceivable jumps of the head between ...
14
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2answers
910 views

What is the difference between DriveSpace and DoubleSpace?

DriveSpace is the successor to DoubleSpace. Both are DOS systems that mount a Compressed Volume File as a drive, allowing ordinary programs to interface with a compressed drive without an intermediate ...
50
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5answers
10k views

Why did base64 win against uuencode?

From the the two methods of encoding 8-bit data as human-readable ASCII, for a time, uuencode format was more popular. USENET 'binaries' groups were filled with uuencoded posts with whatever goodies ...
19
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1answer
640 views

When was the relocatable object module invented?

During the time when programming was done in machine codes, there was no need for object modules; it just wouldn't make sense. People would write the whole program they needed to run in "zeroes and ...
9
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2answers
2k views

Documentation on Windows Explorer Shell Command Files

Windows Explorer Shell Command Files are a feature added to Windows with Internet Explorer 4 (95 / NT 4). They were used in the now-defunct Quick Launch bar to show the desktop, open IE4's Channels ...
10
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1answer
423 views

On-disk structures for Files-11 format (RSX11)

I'm looking for an explanation, or a link to documentation of the on-disk structures of the Files-11 format, that is, the format of disks used by RSX-11 on the PDP-11. Also known as ODS-1, the ...
12
votes
1answer
466 views

How are File Timestamps recorded in classic Mac OS?

When I save a file it has a 'Created At' and 'Updated At' Value saved as well. I would like to know HOW these values are saved? Are they saved as an integer representing a number of seconds since 1904?...
13
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2answers
551 views

What was the end of line convention for text files on the 8-bit Commodores

A two part question: Did an agreed upon convention for end of line (EOL) within text files exist on the 8-bit Commodores? If there was a convention, what was it?
23
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4answers
2k views

What were the differences in floppy disk formats between Amiga and IBM/PC compatible computers?

The capacity in Amiga Old File System format (OFS, OS version 1.x) was 840KB, with the Fast File System ("FFS" (!)) introduced for OS 2.x onwards able to store 880KB. The PC format stored 720KB on the ...
9
votes
3answers
1k views

What format is the (Timex) Sinclair ZX Spectrum SCREEN$/.SCR file

What format is the (Timex) Sinclair ZX Spectrum SCREEN$/.SCR file and how is the fore/background and attribute data encoded within this format?