JFT meaning in Computing ?

tuteeHUB earn credit +10 pts

Answer:

What is Job File Table mean?

The Job File Table (JFT) is a DOS data structure in the Program Segment Prefix (PSP). It starts at PSP offset 0x18 and is 20 bytes long. For each open file handle, DOS stores the index into the System File Table (SFT). A file handle that is returned by open, _open, and other similar functions is simply an index into the JFT where DOS stored the SFT entry index for the file or device that the program opened.

When a program starts, the first 5 entries in the JFT are preconnected to the standard devices. All other handles are marked as closed by setting the value of the entry to 0xFF. The standard devices are initialised as follows:

Handles 0-2 are connected to the console device. During program execution they can get modified (closed, redirected) like any other handle.

Because the size of the JFT in the PSP is limited to 20 bytes, originally only 15 files (20-5 standard devices) could be open at a time. In MS-DOS 2.0, the Extended Job File Table was introduced, which allowed up to 254 files to be opened.

As of MS-DOS 3.30, the size of the JFT can be modified with a call to INT 21h, 67h.

reference

Report

Posted on 12 Nov 2024, this text provides information on Miscellaneous in Computing related to Computing. Please note that while accuracy is prioritized, the data presented might not be entirely correct or up-to-date. This information is offered for general knowledge and informational purposes only, and should not be considered as a substitute for professional advice.

Take Quiz To Earn Credits!

Turn Your Knowledge into Earnings.

tuteehub_quiz

Write Your Comments or Explanations to Help Others



webstory list tuteehub
Miscellaneous in Computing
webstory list tuteehub
Miscellaneous in Computing


Ever curious about what that abbreviation stands for? fullforms has got them all listed out for you to explore. Simply,Choose a subject/topic and get started on a self-paced learning journey in a world of fullforms.

Important Computing Links

open app imageOPEN APP