The Hardware-Software Interface

General purpose computers need to be able to access a variety of IO devices, from long term storage, mouse, keyboard, networking, and more. A device controller/adapter is an electronic circuit capable of operating a specific I/O device. The interface may be set by and/or examined by device drivers. A device driver is a device-specific program that implements I/O…

Disk Block Allocation

The file system sees a file as a series of blocks where the file physically exists on the disk. That disk block can only be accessed as a single unit using low-level read-block and write-block operations.  In a contiguous block allocation scheme, every file is mapped into a contiguous sequence of disk blocks. The FCB points to the…

File Directories

A file directory (or folder) is a special-purpose file that records information about other files and possibly other directories. The directory consists of a set of entries, each containing the name of a file followed by other information necessary to access the file. Directories and folders are technically different, especially under Windows. Windows provides other information about folders,…

Files

Files present a way to store persistent data (that is data that doesn’t go away when a computer is either intentionally, or unintentionally, turned off). Older systems relied on tape, then magnetic disks, and now solid state media. A file system is used by the OS to manager and track the files on the media….