A binary tree is often the easiest type of tree structure to build because it has at most two child nodes. We usually call these child nodes left and right. We add a top node, our first value. The first value is always at the top – and is a special case when creating the…
Errors can occur for several reasons when performing an IO operation. On a read of a disk you could have: a failed write operation the sector go bad due to age/use Additionally you could have issues with data being corrupted during transmission, especially over a long network. Therefore a parity bit is added to a series…
Hard disks are still the most popular form of persistent data storage. Inside a HDD is a series of round platters (disks) that spin. This is a magnetic surface which is read and written to. Most modern HDDs spin in the 7200RPM range or higher. Each platter is made up of a series of tracks,…
A buffer is a register or an area of main memory used to hold data generated by a producer process or an input device and removed from the buffer at a later time by a consumer process or an output device. Depending on the intended use, a single buffer can hold one character at a time or…
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…
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…
Creating or destroying a file effects the FCB with creation creating the FCB and allocating space for the file is only done when there is contents for the file, which often happens almost instantaneously, while deleting/destroying the file means that its resources are released so another use can use it. The Open File Table is…
In addition to the file name, file type, and other meta data, the file system has to keep track of various other pieces of data. How much data is stored is dependent upon the OS and it’s needs. Size – of the file Type – directory / executable file / data file / etc Location…
