Atari DOS and MS DOS filename format.

[peteym5]

Something I have always been wondering is where the file naming standard used in Atari 8-bit DOS and MS DOS, version 1-6.2 came from. That is using the 8 character filename with the 3 character extension. Now the Atari DOS was probably out more than a year before Bill Gates made is contract with IBM as the standard for the PC. Some of us know that Microsoft got their DOS from someone else prior. I am wondering is this standard was taken from a standard on mainframes before that. I know Unix did not use the format, and Commodore and Apple had different file naming standards as well. I am pretty sure Microsoft did not barrow the format that was on the Atari 8-bit system first. The main question is where did the file naming convention come from? That is Eight characters with a 3 character extension. Also using characters followed be a color to represent the device (D1: D2: A: C: P:, etc) Both Disk Operating Systems had some interesting similarities in functionality. I know the user interface is different in one is Menu driven and the other is Command Line, I am referring to how things function.

[Prodos8]

I'd say CP/M as it uses that naming convention and predates MS/PC-DOS and IIRC Atari DOS.

[Rybags]

+1 CP/M

 

I don't know what format midrange OSes of the time, or what Digital Equipment VAXes used.

 

But, IBM mainframe OSes have "Datasets". The format there is 44 characters, with each "level" allowing 8 characters.

 

Why 8.3? I guess one reason might be that on the Atari at least, the information needed for the file fits nicely into 16 bytes.

[WizWor]

I'd say CP/M as it uses that naming convention and predates MS/PC-DOS and IIRC Atari DOS.

I'd agree. Here is an interesting conversation on the same topic...

 

> This has gone beyond that it is worth a 1% bonus in course I'm

> taking (as I mentioned first time around). This is a piece of

> knowledge that could be on the verge of extinction.

>

> Does anybody know?

>

 

The short answer is not really, MSDOS and windows definitely got it from

CPM, and I suspect that CPM picked up the three letter extension stuff from

DEC but expanded the filename size from 6 to 8 letters. (PIP and DDT are

commands available for both DEC & CPM systems so some common ancestory here)

 

I suspect the answer being looked for here is "CP/M" but quite why CP/M used

8.3 is lost (they had two spare bytes in the directory format which could

have been used to give 10.3) .

 

and here...

 

My theories:

 

1. The standard CP/M disk sector size was 128 bytes, and he wanted to have

32-byte directory entries, so that they would come out even ... a whole

number per sector. It had to be a power of 2, anyway. He laid out all the

fields that the directory entry needed according to his file system ideas,

and there were 11 bytes left over for the file name and extension. Since DEC

systems were already using 3-character extensions, which seemed to be a

practical minimum, that left 8 for the name.

 

2. There is evidence that Gary was one of those rare individuals with both

DEC and IBM influences in his background. DEC had established the

3-character file extension as a standard on its systems, and IBM mainframes

of the time had 8 characters as a common namespace size. Put the two

together, and you get 8.3. (BTW, the IBM influence can be seen his his PL/M

language, with PL/I-like syntax and his choice of PL/I for his first

application language compiler.)

[peteym5]

Yes CP/M used this 8.3 format before Microsoft or Atari. I know Atari directory structure had 16 bytes per filename. 11 for the filename, others for attributes, size, and first sector. MS-DOS used 32 bytes because it time-stamped the file and saved other information. I remember Windows 95 still kept the format and the longer filename was stored elsewhere. I remember after hard drive crashes and restoring files, I only had like 6 characters followed by a ~ and a number. Windows XP, probably did away saving to a 8.3 format. The directories were in a standard location on the drive. Most of the available DOSes on the Atari did the same thing, with the major exception being SpartaDOS. Many people use MyDOS because it supports big hard drives and has no compatibility issues.

[WizWor]

Windows XP, probably did away saving to a 8.3 format.

Did away with is probably not the right terminology. If you open a cmd window and do a dir /x you will see the short file names. Not sure how xp stores things internally, but short names are definitely available.