Figure 18.8: Layout of Processes on the Meiko Multicomputer. Each box enclosing
a letter represents a node: trace manager processes are marked ``T,''
computational processes ``C,'' and display manager processes ``D.'' ``H'' is
the system host board, and ``W/S'' represents the Sun workstation, where the
user interface resides. Each trace manager has access to two disk drives
(small circles), and two processors also have 8mm tape drives. The lines
between nodes represent communications channels.
ISIS is implemented on a multicomputer manufactured by Meiko Scientific Ltd. Figure 18.8 is a schematic representation of the prototype ISIS hardware. The trace manager is implemented on eight nodes, each with an Inmos T800 processor and a SCSI controller responsible for two 1.2-gigabyte disk drives. Two of the trace manager nodes also control 8mm tape drives used for initial loading of data into the system. The computational processes reside on eight nodes with Intel i860 processors. The display manager is mapped onto two T800 nodes with video RAM and an RGB analog output that drives a color monitor. The user interface resides on a Sun SPARCstation that serves as the host machine for the Meiko system.
It should be noted that, because the i860 is nearly an order of magnitude faster than the T800, many of the functions of the trace manager and the display manager are actually performed on the computational nodes, but this detail is completely hidden from the applications programmer.
We consider this system a prototype. A simple evaluation of the capabilities of the hardware will show that it cannot provide the performance described in Section 18.2.6. While this machine has proven to be extremely useful, a complete system would be two to four times the size. The system software is designed to be scalable, as is the hardware. In fact, if the size of the machine were doubled, the ISIS software would run as is, without requiring recompilation.