Mobile computers such as notebooks, subnotebooks, and palmtops require low weight, power consumption, good interactive performance. These requirements impose many challenges on architectures operating systems. This paper investigates three alternative storage devices for mobile computers: magnetic hard disks, flash memory disk emulators, cards.We have used hardware measurements trace-driven simulation to evaluate each of the their related design strategies. Hardware an HP OmniBook 300...

It is often desirable, for reasons of clarity, portability, and efficiency, to write parallel programs in which the number processes independent available processors. Several modern operating systems support more than one process an address space, but overhead creating synchronizing kernel can be high. Many runtime environments implement lightweight (threads) user this approach usually results second-class status threads, making it difficult or impossible perform scheduling operations at...

We examine the impact of using flash memory as a second-level file system buffer cache to reduce power consumption and access latency on mobile computer. use trace-driven simulation evaluate what we call FLASHCACHE. relate storage sub-system characteristics FLASHCACHE: its size, unit erasure, costs. find that FLASHCACHE can subsystem by 20-40% improve overall response time 30-70% when combined with an aggressive disk management policy. When more conservative policy, is reduced from 40-70%...

Many different parallel programming models, including lightweight processes that communicate with shared memory and heavyweight messages, have been used to implement applications. Unfortunately, operating systems languages designed for typically support only one model. Multi-model is the simultaneous use of several both across programs within a single program. This paper describes multi-model in Psyche multiprocessor system. We explain why desirable present an system interface it. Through...

It is often desirable, for reasons of clarity, portability, and efficiency, to write parallel programs in which the number processes independent available processors. Several modern operating systems support more than one process an address space, but overhead creating synchronizing kernel can be high. Many runtime environments implement lightweight (threads) user this approach usually results second-class status threads, making it difficult or impossible perform scheduling operations at...

This study presents data from 2 years of extensive sampling July to October at 7 caves and mines used by bats in the Appalachian Mountains region western Maryland southwestern Pennsylvania. In total, 2,860 individuals species were captured. We examined composition roosts compared our a survey conducted 5 same decades ago; up 6 species, has remained stable. addition, we roost fidelity via mark recapture (at 1 cave); population structure; nightly, seasonal, yearly patterns use. Bats exhibited...

This article reports the impact of teachers undertaking practitioner enquiry projects as part their professional development. was a longitudinal study situated across five different schools. In considering within own schools, we offer both framework in terms research orientation/impact grid to identify characteristics successful and an interpretation why some participants were successful, whereas others less with projects. The considers factors faced by teacher-enquirers that may either...

Abstract In the standard kernel organization on a bus‐based multiprocessor, all processors share code and data of operating system; explicit synchronization is used to control access structures. Distributed‐memory multicomputers use an alternative approach, in which each instance performs local operations directly uses remote invocation perform operations. Either approach interkernel communication can be large‐scale shared‐memory multiprocessor. paper we discuss issues architectural features...

Trends in storage technology indicate that future notebook, palmtop, and smaller mobile computers will contain battery-backed DRAM as primary direct-mapped hash memory secondary storage, but no disk. All offer uniform, random access read times through a single-level 64-bit address space. The paper explores the operating system implications of this organization. should exploit benefits having all data reside fast memory. It can do away with much duplication related movement take place...

It is maintained that to exploit fully the parallelism inherent in animate vision systems, an integrated architecture must support multiple models of parallelism. To this claim, hardware base a typical laboratory and software requirements applications are described. A brief overview then given Psyche operating system, which was designed multimodel programming. complex application, checkers, constructed as program under Psyche, also Checkers demonstrates advantages decomposing systems by...

With mobile computers, and increasingly users, a new paradigm for integrated execution must be developed. An environment in which users may move freely among machines from place to place, is described. In such an environment, workstation essentially computer that temporarily provides windows processing power user. The specific implications of mobility, i.e., window systems, process management, internet user naming, network software, server reconfiguration are discussed.< <ETX...

Many different parallel programming models, including lightweight processes that communicate with shared memory and heavyweight messages, have been used to implement applications. Unfortunately, operating systems languages designed for typically support only one model. Multi-model is the simultaneous use of several both across programs within a single program. This paper describes multi-model in Psyche multiprocessor system. We explain why desirable present an system interface it. Through...

An open operating system, which provides a high degree of programming flexibility and efficiency, generally requires that all programs be written in single language no protection other than is available from the compiler. It noted these limitations become unacceptable on workstation must run untrusted software many different languages. Psyche, an system designed to make most effective possible use shared-memory multiprocessors uniprocessor machines, presented. combines with ability write...

Animate vision systems couple computer and robotics to achieve robust accurate vision, as well other complex behavior. These combine low-level sensory processing effector output with high-level cognitive planning—all computationally intensive tasks that can benefit from parallel processing. A typical animate application will likely consist of many tasks, each which may require a different programming model, all must cooperate the desired multi-model programs an underlying software system not...