Nominal Hardware Costs

 For the purposes of computing the cost of your cache design you may assume the following cost relationships.

1.

Each individual tag within the tag memory of your cache costs 2 ECU.

2.

Each 32-bit word of memory within the data portion of your cache costs 1/2 ECU.

3.

The cost of the cache controller depends upon the complexity of the policy decisions you have chosen. A basic controller, with a WT write policy, a RND replacement policy, and either of the two write allocation policies, costs 100 ECU. If you choose to use LRU replacement you must add 50 ECU to this, and if you choose to use a CP write policy you must also add 50 ECU to the controller cost.

4.

You may assume that the cache requires logic to detect a hit/miss outcome from tag interrogations, and that this costs $(A-1)\times 100$ ECU, where A is the degree of associativity. Thus, the hit detection logic for a direct-mapped cache (for which A=1) costs nothing; for a two-way set-associative cache it costs 100 ECU, and for a four-way set-associative cache it costs 300 ECU.

Thus, your final table of costs may look something like table 4, but with the ``-'' and ``??'' entries replaced by actual values.

 

 

Tags 2 - -

Data words 1/2 - -

Basic controller 2 - -

LRU logic 50 - -

CB logic 50 - -

Hit logic (A=??) 100 ??-1 -

3|rGrand total -