Flynn's classification examine the behavioural concept and does not receive into consideration the computer's structure. Parallel computers can be classified stand on their structure also, which is discussed under and shown in Figure 8.
As we have know, a parallel computer (MIMD) can be characterised as a set of multiple processors and memory modules or shared memory communicating via an interconnection network. When multiprocessors commune through the global shared memory modules then this organisation is called as tightly coupled systems or Shared memory computer as shown in Figure 9. Similarly, when each processor in a multiprocessor system, have its own local memory and the processors commune via messages transmitted among their local memories, then this organisation is said as Loosely coupled system or Distributed memory computer as shown in Figure 10. Figures 9 and 10 show the easy diagrams of both organisations.
The memory and processors in both organisations are interrelated via an interconnection network. This interconnection network may be in dissimilar forms like multistage network, crossbar switch, etc. which will be discussed in the next unit.