An increasing number of libraries are seeking to provide access to CD-ROM products from the same peripheral devices as are used to access their automated library systems. There are two principal options, one for access from PCs, the other for access from ASCII (“dumb”) terminals.
PC Access-This approach to CD-ROM access uses PCs to access a CD-ROM server, usually over a Novell Local Area Network (LAN). The PC approach can support full graphics displays and high-quality audio. This is particularly important if some of the CD-ROM products include multimedia. Depending on the configuration, frequently accessed information can be loaded on the server's hard drive and disk caching can be used to provide rapid access.
ASCII Terminal Access—This approach to CD-ROM access uses dumb terminals which support VT-100 terminal emulation—something which most terminals on automated library systems can do. Terminals can only access text, not graphics and audio. The connection is usually, but not always, made over a Telnet-based link through a UnixWare server to the CD-ROM server. This approach does not work well with all CD-ROM products because the product's design may assume the use of special function keys on PCs.
Either approach may support up to seven or eight users accessing the CD-ROM server concurrently.
Most automated library system vendors will work with libraries in implementing the first option. A few provide a full range of products and services, including CD-ROM servers, CD-ROM towers and drives, and development of menus. When a library proceeds without the active participation of its vendor, it should be careful to avoid the installation of a “foreign” server (one from another vendor) between the PCs and the automated library system's central site because the vendor will not then assume responsibility for response times. Instead, the CD-server and the automated library system should each function independently, with each accessed directly over cabling which is used for both applications.
Only a few vendors will undertake mapping of CD-ROM products so that terminal commands match up with the commands anticipated by the CD-ROM software. When this service is not provided by the vendor, it may be better to substitute PCs for dumb terminals at those locations where access to both the automated library system and CD-ROM drives is wanted from a single device.
An approach which the contributing editor favors is implementing an OPAC with 50 percent dumb terminals and 50 percent PCs. The former are on standing-height tables and are for users who are seeking brief catalog look-up. The latter are installed in carrels and are designed to facilitate not only extended use of the OPAC, but also access to CD-ROM products.