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A direct-access storage device (DASD) (pronounced / ˈ d æ z d iː /) is a secondary storage device in which "each physical record has a discrete location and a unique address". The term was coined by IBM to describe devices that allowed random access to data, the main examples being drum memory and hard disk drives . [ 1 ]
Operating System/Virtual Storage 1 (OS/VS1) Operating System/Virtual Storage 2 R1 (OS/VS2 SVS) PRIMOS (written in FORTRAN IV, that didn't have pointers, while later versions, around version 18, written in a version of PL/I, called PL/P) Virtual Machine/Basic System Extensions Program Product (BSEPP or VM/SE)
Fixed-block architecture (FBA) is an IBM term for the hard disk drive (HDD) layout in which each addressable block (more commonly, sector) on the disk has the same size, utilizing 4 byte block numbers and a new set of command codes. [1]
The 1980s saw the minicomputer age plateau as PCs were introduced. Manufacturers such as IBM, DEC and Hewlett-Packard continued to manufacture 14-inch hard drive systems as industry demanded higher storage; one such drive is the 1980 2.52 GB IBM 3380. But it was clear that smaller Winchester storage systems were eclipsing large platter hard drives.
The underlying device is still location-addressable, but the operating system of a computer provides the file system abstraction to make the operation more understandable. In modern computers, secondary, tertiary and off-line storage use file systems.
Some solid-state storage devices use RAM and a battery that preserves the contents of the RAM without system power as long as the battery continues to provide power. Flash-based storage does not suffer the limitation of a battery, but RAM-backed storage is faster and does not experience write amplification. [3] [8] [9]
The operating system must manage the bank-switching operation to ensure that program execution can continue when part of memory is not accessible to the processor. Bank switching is a technique used in computer design to increase the amount of usable memory beyond the amount directly addressable by the processor [ 1 ] instructions.
Hardware architecture is the representation of an engineered (or to be engineered) electronic or electromechanical hardware system, and the process and discipline for effectively implementing the design(s) for such a system. It is generally part of a larger integrated system encompassing information, software, and device prototyping. [2]