- Another popular MIN is the
Omega MIN
- The interconnections
between the stages in
a Omega Network
are defined by the
"rotate left"
of the bits used in the port IDs.
- Example:
An 8 x 8 Omega Network is interconnected as follows:
000 ---> 000 ---> 000 ---> 000 001 ---> 010 ---> 100 ---> 001 010 ---> 100 ---> 001 ---> 010 011 ---> 110 ---> 101 ---> 011 100 ---> 001 ---> 010 ---> 100 101 ---> 011 ---> 110 ---> 101 110 ---> 101 ---> 011 ---> 110 111 ---> 111 ---> 111 ---> 111 - Pictorially:
- How to read the figure:
- Pick a number at the left (e.g., 4 = 100)
- Rotate left: 100 ---> 001 (= 1)
- Connect 4 to 1
You have to do this in every stage
- The Omega network operates in the same manner as
the Delta network,
so I will be pretty brief in examples.
- Example Forwarding in Omega network
- CPU 1 sends a request (address value) to memory model 4.
- Step 0: initial situation
- Step 1:
- Step 2:
- Step 3:
- It works in a similar manner as the
Delta Network.
- This figure illustrates the paths taken by
the different routing tags:
- You can see that the first and the third Banyan
switch in Stage 2
will receive requests that have address tags starting with
0xx
- The second and the fourth Banyan
switch in Stage 2
will receive requests that have address tags starting with
1xx
- These addresses are then further "sorted" on their
second bit by
the Banyan switches in
Stage 3
- Please don't ask me how the designer came up with the design.... I only know how it works, not how he came up with the idea... Maybe long nights zipping on barrels of coffee :-)
- Omega network has the same "internal blocking"
problem as the Delta network.
- Omega network has the property that:
- Each stage is interconnected in the SAME manner
This can be highly desirable in manufacturing (making the same copy...)