The choice of a server is very important when dealing with large numbers of students running instructional lessons which use digital video. Both processor speed and bus speed are critical. When running digital video 32 bit PCI or MC ethernet cards work better ISA bus cards. The machine running our system, Figure 15, is a 66 MHz 486 with 32 MB RAM IBM server which has dual 32 bit full duplex ether streamer ethernet cards. With about 180 students attached to this machine utilization is under 20%.
The operating system is Novell 4.1 running in NDS mode. This is a very efficent system for transferring files from the server to the student machines. Novell Netware can also facilitate transfer of video files from the server to the student computer by sending consecutive pieces of the video file without waiting for an acknowledging signal from the student computer.
Although the Novell Opering System controls access to the lessons, users never sign on with the Novell login procedure. Our software automatically logs users onto the system in the appropriate mode.
Figure 15, Netware server use to run interactive video lessons.
The WEB server, Figure 16, is a 90 MHz Pentium with full duplex PCI ethernet cards running Windows NT Server 3.51 as the operating system and Netscape Commerce Server as the Web server software.
This on-line paper is running on this machine.
Figure 16, WEB Server