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--- verilog_modules [2007/11/16 01:18] – roumani
+++ verilog_modules [2007/11/16 01:29] (current) – roumani
@@ Line 2: / Line 2: @@
 So far we have been writing Verilog top-level modules that test components. In this lecture we learn how to write te components themselves.
 ===== Outline =====
-  * Performing PC+4 using the main ALU
+A Verilog top-level (i.e. ''main'') module consists of the following section:
-  * Performing PC+4 + 4*Label using the main ALU
-  * Adding registers to hold intermediate data
-  * Combining the two memory units
-  * Issuing the control signals for State #0
-  * Doing something useful in State #1
-  * Instruction-dependent states
+  * A ''module'' header
+  * A //declaration// block
+  * A //circuit// block where all the needed components are instantiated and connected via ''assign''.
+  * One ''initial'' block
+  * One or more ''always'' blocks.
+A Verilog component (i.e. reusable in other modules) differs slightly from a top-level module as indicated below:
+  * The ''module'' headers is followed by //ports//, the names of the wires that connect this component to the outside world.
+  * The declaration section indicates which wire is incoming (by using ''input'') and which is outgoing (using ''output'').
+The functionality of the component can be implemented procedurally (in an ''always'' block) or structurally (in the circuit instantiation section).
-===== To Do =====
-  * Unordered List Item
-  * Unordered List Item
-   * Look at the program ''alu1b'' and its tester ''alu1bClient'' in the //Resource Directory//. ''alu1b' is a 1-bit adder component made up of basic gates.
-  * Look at the program ''alu2b'' and its tester ''alu2bClient'' in the //Resource Directory//. ''alu2b' is a 2-bit adder component made up of two ''alu1b'' adders.
+===== To Do =====
+  * Look at the program ''alu1b'' and its tester ''alu1bClient'' in the //Resource Directory//. ''alu1b'' is a 1-bit adder component made up of basic gates.
+  * Look at the program ''alu2b'' and its tester ''alu2bClient'' in the //Resource Directory//. ''alu2b'' is a 2-bit adder component made up of two ''alu1b'' adders.