Literature Scrolled displays out Hierarchically paged displays are more efficient than scrolling displays except with more able subjects where there was little difference. These results show that the choice of a particular display can affect performance of its operators according to their ability. The experiments were carried out on 23 subjects at the Department of Applied Psychology at UWIST who had to locate faults in a network of units. The hierarchi&ly paged display contained a 6 x 9 network considered as nine pages, each 2 x 3, with connections between adjacent pages. In the scrolling display a page-sized window was provided with scrolling left, right, up or down by
More bits of output Working with digital image display terminals, it is helpful to have some knowledge of the nature of the colours that can be displayed. Such understanding helps obtain high quality displays and is essential to applications requiring real colour. A paper by A. Santisteban (IBM J Res Dev 27 (1983) 127) seeks to provide this service for IBM’s Hacienda image processing system. It has 1024 x
typing a key letter. Speed of fault-finding did not vary significantly for the two types of display, but fewer errors were made with the hierarchically paged display. Lowability subjects scored worse with the scrolling display, and there was little difference in the other three permutations of subject ability and display type. What the researchers did not expect to find was that restricting the proportion of the system displayed improved the consistency of performances between subjects. This, they think, may prove a useful consideration for the systems designer when estimating overall reliability. J.B. Brooke, K.D. Duncan Ergonomics 26 (1983) 465
1024 refresh buffer locations with 12 image data bits and a 15-bit video lookup table. 4 096 colours are simultaneously displayable from a menu of 32 768. Proposals for describing the discrete set of colours displayable are based on the CIE 1976 colour space (which uses an intensity-hue-saturation perceptual basis). Results obtained suffice ia first approximation applicable to similar displays, the author claims. He concludes
Visual display units introduced to the working environment must be well integrated with less strenuous, manual procedures. This is essential, according to the Swedish National Board of Gccupational,Safety and Health, if stress and visual strain are to be avoided (E. Gunnarsson, I. siiderberg Appl Erg 14 (1983) 61). The board conducted an experiment in the sales office and directory enquiries departments of the Swedish Telecommunications Administration. VDU users, 15 from the former location and 30 from the latter, were divided into two age groups and asked to perform tasks at ‘normal’ and ‘intensified’ levels. Effects of the work were assessed qualitatively, by questionnaire, and quantitatively, by measurement of near points of accommodation and convergence. Results revealed the importance of factors such as work spell duration and rigidity of work routines. that it is advisable to design imageprocessing VDUs with the greatest possible number of outnut bits from the video look-up table. Th;! number of image data bits in the refresh buffer need not be so high.
the authoritative international journal on microcomputer technology
Further details, including subscription rates from: Christine Mullins Butterworth Scientific Limited - Journals Division PO Box 63 Westbuty House Bury Street Guildford Surrey GU2 5BH England Telephone: 0483 31261
DISPLAYS. OCTOBER 1983