54 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 ...
  • 21.3k
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 ...
  • 29.2k
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 ...
  • 183k
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 ...
  • 183k
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 ...
20 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 ...
  • 2,620
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
7 votes

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

UNFORMAT has two modes of operation. The first one restores a backup of the critical areas of the disk, a “Mirror” backup. These backups are created, space permitting, by the MIRROR tool and by FORMAT ...
5 votes

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

My recollection of this is that at some point Microsoft made the default behaviour of the FORMAT command so it would save a copy of the file system somewhere. So if you did a format and then realised ...
5 votes

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

The $ suffix was meant to fence off the Microsoft-reserved namespace. It works the way the __ prefix fences off the implementation-reserved namespace in C and C++. Similar to C and C++, DOS had a long ...
5 votes

How did the Spectrum clones with TR-DOS and paged memory load and run code files from disk?

How it [likely] works When ZX-Spectrum with Beta interface (re)starts, Beta Disk Interface sets ROM_CS flag to disable its builtin ROM and connects TR-DOS ROM to initialize the interface, dirves, and ...
  • 51
5 votes

Origin of the 8.3 file names scheme

If you think of memory restrictions, small file names make more sense. You would want a directory structure allocating maybe 32 bytes to each directory entry. Those bytes would include the file name,...
  • 8,223
3 votes

How do I know where the file directory is stored on a Spectrum +3 disk layout?

I know this is an old thread, but I've recently come across the same problem. In the end, I realized that there are three possible disk formats I need to be aware of, so I write my disk initialisation ...
  • 31
1 vote

How did the Spectrum clones with TR-DOS and paged memory load and run code files from disk?

TR-DOS programs are usually started as BASIC ones, by loading *.B file a number of bytes given in the file descriptor. No sector size is honored this time and loading address is essentially ignored (...
  • 9,446

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