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DECtape II
DECtape, originally called Microtape, is a magnetic tape data storage medium used with many Digital Equipment Corporation computers, including the PDP-6, PDP-8, LINC-8, PDP-9, PDP-10, PDP-11, PDP-12, and the PDP-15. On DEC's 32-bit systems, VAX/VMS support for it was implemented but did not become an official part of the product lineup. DECtapes are wide, and formatted into blocks of data that can each be read or written individually. Each tape stores 184K 12-bit PDP-8 words or 144K 18-bit words. Block size is 128 12-bit words (for the 12-bit machines), or 256 18-bit words for the other machines (16, 18, 32, or 36-bit systems). From a programming point of view, because the system is block-oriented and allows random seeking, DECtape behaves like a very slow disk drive. Origins DECtape has its origin in the LINCtape tape system, which was originally designed by Wesley Clark at the MIT Lincoln Laboratory as an integral part of the LINC computer. There are simple LINC instructions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DECTape Unit For The DEC PDP-11
DECtape, originally called Microtape, is a magnetic tape data storage medium used with many Digital Equipment Corporation computers, including the PDP-6, PDP-8, LINC-8, PDP-9, PDP-10, PDP-11, PDP-12, and the PDP-15. On DEC's 32-bit systems, VAX/VMS support for it was implemented but did not become an official part of the product lineup. DECtapes are wide, and formatted into blocks of data that can each be read or written individually. Each tape stores 184K 12-bit PDP-8 words or 144K 18-bit words. Block size is 128 12-bit words (for the 12-bit machines), or 256 18-bit words for the other machines (16, 18, 32, or 36-bit systems). From a programming point of view, because the system is block-oriented and allows random seeking, DECtape behaves like a very slow disk drive. Origins DECtape has its origin in the LINCtape tape system, which was originally designed by Wesley Clark at the MIT Lincoln Laboratory as an integral part of the LINC computer. There are simple LINC instructio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lincoln Laboratory
The MIT Lincoln Laboratory, located in Lexington, Massachusetts, is a United States Department of Defense federally funded research and development center chartered to apply advanced technology to problems of national security. Research and development activities focus on long-term technology development as well as rapid system prototyping and demonstration. Its core competencies are in sensors, integrated sensing, signal processing for information extraction, decision-making support, and communications. These efforts are aligned within ten mission areas. The laboratory also maintains several field sites around the world. The laboratory transfers much of its advanced technology to government agencies, industry, and academia, and has launched more than 100 start-ups. History Origins At the urging of the United States Air Force, the Lincoln Laboratory was created in 1951 at the Massachusetts Institute of Technology (MIT) as part of an effort to improve the U.S. air defense syste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drum Memory
Drum memory was a magnetic data storage device invented by Gustav Tauschek in 1932 in Austria. Drums were widely used in the 1950s and into the 1960s as computer memory. Many early computers, called drum computers or drum machines, used drum memory as the main working memory of the computer. Some drums were also used as Auxiliary memory, secondary storage as for example various IBM_drum_storage, IBM drum storage drives and the UNIVAC FASTRAND series of drums. Drums were displaced as primary computer memory by magnetic core memory, which offered a better balance of size, speed, cost, reliability and potential for further improvements. Drums were then replaced by hard disk drives for secondary storage, which were both less expensive and offered denser storage. The manufacturing of drums ceased in the 1970s. Technical design A drum memory or drum storage unit contained a large metal cylinder, coated on the outside surface with a ferromagnetic recording material. It could be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Disk
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, platters coated with magnetic material. The platters are paired with disk read-and-write head, magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual Block (data storage), blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data when powered off. Modern HDDs are typically in the form of a small disk enclosure, rectangular box. Hard disk drives were introduced by IBM in 1956, and were the dominant secondary storage device for History of general-purpose CPUs, general-purpose computers beginning in the early 1960s. HDDs maintained this position into the modern er ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timesharing
In computing, time-sharing is the concurrent sharing of a computing resource among many tasks or users by giving each task or user a small slice of processing time. This quick switch between tasks or users gives the illusion of simultaneous execution. It enables multi-tasking by a single user or enables multiple-user sessions. Developed during the 1960s, its emergence as the prominent model of computing in the 1970s represented a major technological shift in the history of computing. By allowing many users to interact concurrently with a single computer, time-sharing dramatically lowered the cost of providing computing capability, made it possible for individuals and organizations to use a computer without owning one, and promoted the interactive use of computers and the development of new interactive applications. History Batch processing The earliest computers were extremely expensive devices, and very slow. Machines were typically dedicated to a particular set of ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swap File
In computer operating systems, memory paging is a memory management scheme that allows the physical memory used by a program to be non-contiguous. This also helps avoid the problem of memory fragmentation and requiring compaction to reduce fragmentation. Paging is often combined with the related technique of allocating and freeing ''page frames'' and storing pages on and retrieving them from secondary storage in order to allow the aggregate size of the address spaces to exceed the physical memory of the system. For historical reasons, this technique is sometimes referred to as ''swapping''. When combined with virtual memory, it is known as ''paged virtual memory''. In this scheme, the operating system retrieves data from secondary storage in blocks of the same size (pages). Paging is an important part of virtual memory implementations in modern operating systems, using secondary storage to let programs exceed the size of available physical memory. Hardware support is nece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OS/8
OS/8 is the primary operating system used on the Digital Equipment Corporation's PDP-8 minicomputer. PDP-8 operating systems which precede OS/8 include: * R-L Monitor, also referred to as MS/8. * P?S/8, requiring only 4K of memory. * PDP-8 4K Disk Monitor System * PS/8 ("Programming System/8"), requiring 8K. This is what became OS/8 in 1971. Other/related DEC operating systems are OS/78, OS/278, and OS/12. The latter is a virtually identical version of OS/8, and runs on Digital's PDP-12 computer. Digital released OS/8 images for non-commercial purposes which can be emulated through SIMH. Overview OS/8 provides a simple operating environment that is commensurate in complexity and scale with the PDP-8 computers on which it ran. I/O is supported via a series of supplied drivers which uses polled (not interrupt-driven) techniques. The device drivers have to be cleverly written as they can occupy only one or two memory pages of 128 12-bit words, and have to be able to run in any ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operating System
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for efficient use of the system and may also include accounting software for cost allocation of Scheduling (computing), processor time, mass storage, peripherals, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computerfrom cellular phones and video game consoles to web servers and supercomputers. , Android (operating system), Android is the most popular operating system with a 46% market share, followed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linc-8
LINC-8 is the name of a minicomputer manufactured by Digital Equipment Corporation between 1966 and 1969. It combines a LINC computer with a PDP-8 in one cabinet, thus being able to run programs written for either of the two architectures. Architecture The LINC-8 contains one PDP-8 CPU and one LINC CPU, partially emulated by the PDP-8. At any one time, the computer is in either 'LINC mode' or 'PDP-8 mode' - both processors can not run in parallel. Instructions are provided to switch between modes. In the LINC-8, all interrupts are handled by the PDP-8 CPU, and programs that rely on the interrupt architecture of the LINC can not be run. The LINC is a 12-bit ones' complement accumulator machine, whereas the PDP-8, while also a 12-bit accumulator machine, operates in two's complement arithmetic. Memory addressing on the two architectures is also different. On the LINC, the full address space is divided into 1024-word ''segments'', two of which are selected for use at any one time: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDP-5
The PDP-5 was Digital Equipment Corporation's first 12-bit computer, introduced in 1963. History An earlier 12-bit computer, named LINC has been described as the first minicomputer and also "the first modern personal computer." It had 2,048 12-bit words, and the first LINC was built in 1962. DEC's founder, Ken Olsen, had worked with both it and a still earlier computer, the 18-bit 64,000-word TX-0, at MIT's Lincoln Laboratory. Neither of these machines was mass-produced. Applicability Although the LINC computer was intended primarily for laboratory use, the PDP-5's 12-bit system had a far wider range of use. An example of DEC's "The success of the PDP-5 ... proved that a market for minicomputers did exist" is: * "Data-processing computers have accomplished for mathematicians what the wheel did for transportation" * "Very reliable data was obtained with ..." * "A PDP-5 computer was used very successfully aboard EvergreenU. S. Coast Guard Oceanographic Vessel — ''Ever ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDP-4
The PDP-4 was the successor to the Digital Equipment Corporation's PDP-1. History This 18-bit machine, first shipped in 1962, was a compromise: "with slower memory and different packaging" than the PDP-1, but priced at $65,000 - less than half the price of its predecessor. All later 18-bit PDP machines (PDP-7, 7, PDP-9, 9 and PDP-15, 15) are based on a similar, but enlarged instruction set, more powerful than, but based on the same concepts as, the 12-bit PDP-5/PDP-8 series. Approximately 54 were sold. Hardware The system's memory cycle is 8 microseconds, compared to 5 microseconds for the PDP-1. The PDP-4 weighs about . Mass storage Both the PDP-1 and the PDP-4 were introduced as paper tape-based systems. The only use, if any, for IBM-compatible 200 Magnetic tape data storage#Bytes per inch, BPI or 556 BPI magnetic tape was for data. The use of "mass storage" drums - not even a megabyte and non-removable - were an available option, but were not in the spirit of the “per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDP-1
The PDP-1 (Programmed Data Processor-1) is the first computer in Digital Equipment Corporation's PDP series and was first produced in 1959. It is known for being the most important computer in the creation of hacker culture at the Massachusetts Institute of Technology, Bolt, Beranek and Newman, and elsewhere. The PDP-1 is the original hardware for one of the first video games, Steve Russell's 1962 game '' Spacewar!.'' Description The PDP-1 uses an 18-bit word size and has 4096 words as standard main memory (equivalent in bit size to 9,216 eight-bit bytes, but in character size to 12,388 bytes since the system actually divides an 18-bit word into three six-bit characters), upgradable to 65,536 words. The magnetic-core memory's cycle time is 5.35 microseconds (corresponding roughly to a clock speed of 187 kilohertz); consequently most arithmetic instructions take 10.7 microseconds (93,458 operations per second) because they use two memory cycles: the first to fetch the instruc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
