52 votes

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

If you format a drive with quick format option (FORMAT /Q), it only clears the root directory and FAT area, but before doing so, the format command stores them in unused area of the disk. This is ...
  • 19.6k
49 votes
Accepted

Origin of the 8.3 file names scheme

It was because the fairly common 6.3 scheme of the time was considered too small :-) Seriously: 8.3 wasn't a particularly onerous restriction at the time. Many PDP-11 operating systems had a 6 ...
  • 28.5k
44 votes

Filesystems with versioning

FILES-11 on DEC minicomputers was a versioned file system -- RSX-11M, IAS (on PDP-11), VMS (on VAX, Alpha). Version numbers are very user-visible; they are part of the syntax for specifying a file. ...
  • 28.5k
38 votes
Accepted

Why did MacOS Classic choose the colon as a path separator?

Colon was inherited from SOS for the Apple III Unlike one may assume, MacOS (1984/01) did not inherited the colon (:) from Lisa OS (1983/01), which used a hyphen (-) as path separator, but from Apple ...
  • 177k
38 votes
Accepted

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

Quick partial answer: CON, LST, PRN and AUX (*1) are names inherited from CP/M, either direct form its BIOS or CP/M's main file handling utility PIP (*2). NUL was add with DOS. DOS 1.x added ...
  • 177k
37 votes
Accepted

What was the point of Apple Pascal having its own file system?

UCSD Pascal was a product of UCSD - The University of California at San Diego. It was not a product of Apple. UCSD Pascal was available on a number of machines, including the PDP-11, TI99/4, the BBC ...
  • 7,824
35 votes
Accepted

Where was the DOS cdd utility from?

I remember CDD as a 4DOS command, which would have been available in the Norton Utilities as NDOS. JP Software’s other shells also implement CDD, so 4OS2 and 4NT users would probably recognise it too. ...
  • 98.2k
34 votes

How can I recover the contents from an Amiga HDD using modern Linux?

You should be able to use the Amiga hard drive directly on your Linux computer (provided it still has IDE support). Linux also understands AFFS (Amiga Fast File systems), at least once AFFS support ...
  • 28.6k
32 votes
Accepted

When did files start to be dated?

CTSS, a timesharing system for the IBM 7090, was putting dates on files as early as 1962. Timestamps is another story. Wikipedia
  • 4,538
31 votes
Accepted

Why does the single dot entry exist in file systems?

It simply makes sense to have a symbol that stands for the current directory. It makes sense for the symbol to be easy to type and to stand out from ordinary directory names. Dot is a pretty good ...
  • 4,538
31 votes

Origin of the 8.3 file names scheme

[Part of what is described here can be found on Herb Johnson's great site about CP/M history, the other is experience of 30+ years in mainframe procedure] CP/M was, Dave explains, heavily influenced ...
  • 177k
30 votes

How did the /dev file system work in early Unix?

In 1986 (and for a few years after that still), /dev wasn’t handled by a special file system. It was generally a directory on the root file system, and its contents were largely static: a series of ...
  • 98.2k
27 votes

Why did ScanDisk exist?

There are quite a few differences between the MS-DOS CHKDSK and ScanDisk, beyond the latter’s friendlier interface. ScanDisk can “repair” cross-linked files, i.e. files which end up pointing (...
  • 98.2k
26 votes

Why did MacOS Classic choose the colon as a path separator?

I think the colon deserves to be considered the original, the one true separator character. All others are mere imitators ;-) My rationale for this is the seminal paper A General-Purpose File System ...
  • 28.5k
25 votes

What was the point of Apple Pascal having its own file system?

UCSD Pascal was developed prior to the Apple II, during the 70's in San Diego, using PDP-11 class machines with a 512-byte block disk structure. In the process of porting it to microcomputers, often (...
  • 177k
25 votes

Why did MacOS Classic choose the colon as a path separator?

The original Macintosh File System did not support directories. But the Mac did support multiple floppy drives from the start, and colon : was used in fairly standard fashion as a drive prefix ...
  • 10.2k
25 votes
Accepted

Why can MS-DOS not read partitions starting at logical sector 0?

This is a consequence of a buggy overflow check. Internally, MS-DOS uses logical block addressing to access file systems. Since version 4.0, MS-DOS uses 32 bits for sector addresses in order to ...
  • 17.6k
25 votes

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

As Raffzahn explains, the clock device driver was added in DOS 2.0. CON, AUX, etc. were device names already present in DOS 1.0, some of them even earlier in CP/M; these names couldn’t be changed to ...
  • 98.2k
24 votes

Filesystems with versioning

There were quite a few operating systems that had file versioning in the same era as unix. Many file systems that we are familiar with today just have some components of a file name, such as: Name....
23 votes
Accepted

Slash versus backslash as directory separator – what/who caused this rift?

PC/MS-DOS 1 used the slash (/) as the command line switch indicator (like DEC's RSX11 and DG's RTOS before), so when DOS 2.0 introduced subdirectories, they did need a new one. Backslash (\) came ...
  • 177k
23 votes
Accepted

How did Commodore drives produce program listings from disk directories?

TL;DR: The computer, or rather its OS, has no idea about a directory, in fact not even what constructs a file. It can only open/read/write/close data streams from devices on the bus. Getting a ...
  • 177k
21 votes
Accepted

Filesystems with versioning

I am not personally aware of any operating system in the entire history of computing ever having had this feature. Siemens BS2000 of the early 1970s may be an example here (*1) with a feature they ...
  • 177k
21 votes

When did files start to be dated?

I know that a Real Time Clock was not implemented and that the first computer to integrate the RTC was the IBM PC/AT in 1984. There where many more before that. All the way back in the 60s. When did ...
  • 177k
19 votes

How did the /dev file system work in early Unix?

Just a supplement to what Stephen Kitt already said: The entries in any directory in a classic Unix file system are hard links that map names to inodes —small fixed-size records in the file system. ...
  • 1,844
19 votes
Accepted

What was the first file system?

My second guess is CTSS. It was operational in 1961, but at that time had only tapes for user file storage. I suppose that tape name records don't constitute 'metadata' in the sense required by this ...
  • 28.5k
19 votes

Where and when did the ".s" suffix for assembly-language source files originate?

I asked Ken Thompson. The s stands for source, because it was the only source at the time.
  • 291
19 votes
Accepted

Why would an implementation of getwd call mktemp?

If you look into the source code for SunOS 4.1.4, available online, getwd() is not a simple function. It actually walks up the directory tree, performing all sorts of wonderful tasks to get the name ...
  • 2,600
18 votes
Accepted

Where was the Willowsoft Overture File System (OFS1) used?

Documents such as this expand slightly on the attribution of 19h to Willowtech Photon COS with: Code 19H is Claimed for Willowtech Photon COS by Willow Schlanger. So Willowtech was either an ...
17 votes
Accepted

Single level file directory

The whole CP/M family of operating systems, until Concurrent DOS, had both a limited number of files per drive and no hierarchy except for user areas. From the Wikipedia article: CP/M 2.2 had no ...
17 votes

Single level file directory

Most early microcomputer operating systems were single-level - Apple DOS, CP/M, MS-DOS/PC-DOS prior to version 2.0, UCSD P-System, whatever Commodore called their DOS for the PET/CBM and C64. With the ...
  • 1,290

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