Interfaces in Computing最新文献

Because computer graphics displays are using more non-alphanumeric symbolism to facilitate human-computer communication, graphic design, a discipline concerned with systematic information-oriented communication, is important in the design of the “corporate identity” of the human-computer interface. Principles of applied visual semiotics can be used to critique and create these dialogues. Case studies of the Star, Lisa and Metaform office automation systems are analyzed.

In this paper the implementation of CV, a utility for calling up the Versados system under Unix, is described. CV provides useful resource-sharing features to Unix users such as file transfers between the two systems and accessibility of a real-time environment. The implementation of the Unix-to-Versados link requires detailed knowledge of the hardware and software interfaces of the systems. Problems encountered and their solutions are discussed; the experience gained here could be useful to others in solving similar problems.

The continuous acquisition of experimental time functions by an integrating analogue-to-digital conversion technique is discussed. The theoretical justification of the procedure's superiority over schemes based on point measurement, with special regard to its intrinsic noise rejection, and an appropriate mathematical method for the computer internal representation and processing of empirical functions are given. Then, the hardware design of a corresponding multichannel interfacing unit, its physical interconnection with minicomputers and/or microcomputers and the required software support are described. The technique yields considerable complexity and work load reductions and eases time constraints.

In local area networks with token-controlled access to the physical medium, the access rights are passed from one station (or node) to another by transferring a token. There is only one token owner at a time which controls the packet generation onto the physical medium. Token-controlled systems are deterministic, in contrast with systems controlled by carrier sense multiple access with collision detection (CSMA/CD), and therefore worst case access times or transaction times can be defined, which is an important characteristic in distributed process control systems. In this paper a token-passing scheme is described which may be added below a commercially available data link controller with CSMA/CD control. The performance of the two access protocols is compared.

Multimodule boards and the SBX bus concept allow system expansion by small increments, to take advantage of the latest technological achievements. The special requirements of diverse applications can also be satisfied by user-designed multimodules. In this paper a user-designed multimodule is presented which offers man-machine interfacing capabilities for a digital controller based on the SBC 88/40 microcomputer.

Diagnostic test and verification tools are required to run and develop Fastbus networks. In particular, on-line program developments demand standard target modules and visual feedback of the actual bus status from a Fastbus segment during specific cycles. The two basic hardware units to provide this are a standard Fastbus slave and a cycle-latching logic which can be connected to a direct back-plane status display. The diagnostic applications are therefore threefold: the separate use of the test slave or of the latch logic, or a combined use of both of them. The combined use allows the verification of test slave cycles through the latch circuitry, revealing the corresponding bus pattern for all Fastbus signals. The Fastbus display module (FDM) developed at CERN integrates both the Fastbus slave and the latch and display logic on one card. FDM-specific test software is being developed.

In this paper, experiments carried out to measure data throughput between an LSI 11/23 computer and a VAX 11/750 computer over an Ethernet local area network are described. Data were transferred from the LSI to the VAX in three experiments to study the effect of memory-to-memory, memory-to-disc and disc-to-disc data transfer with respect to packet size and acknowledge window size. The results show data throughput to range from 0.86 to 0.49 Mbits s⁻¹ and suggest where the rate-limiting processes are located.

Recent media interest in artificial intelligence (AI) (mainly through commercial exploitation of expert systems) and programming languages used within the field can only be sustained and built upon if those interested possess an overall awareness of the background against which most AI research is undertaken. AI has a small, although growing, fundamental base of core theory; it attacks difficult problems by expedient means and pioneering effort and aims to generate sufficient or adequate solutions which can themselves be refined and then perhaps incorporated into the fundamentals of AI theory.

In this paper the design and operation of an analogue-to-digital (A/D) converter and a digital-to-analogue (D/A) converter interfaced to an AIM-65 8-bit microcomputer are described. These converters are built from integrated circuits on two separate printed-circuit cards. The A/D card also incorporates an eight-channel multiplexer, and the D/A card has a latch that keeps the output constant while the data acquisition takes place.