Computer Architecture & Operations I Instructor: Ryan Florin

Integrated Circuit Integrated Circuit (IC) Classifications A small electronic device made out of a semiconductor material Classifications SSI (small-scale integration) up to 100 electronic components per chip MSI (medium-scale integration) 100~3,000 electronic components per chip LSI (large-scale integration) 3,000~100,000 electronic components per chip VLSI (very large-scale integration) 100,0000 to 1,000,0000 electronic components per chip ULSI (ultra large-scale integration) More than 1 million electronic components per chip

Decoder Decoder A logic block that has n-bit input and 2n outputs, where only one output is asserted for each input combination If the input is i (in binary), then output i is 1 others are 0

Decoder Example 3-8 Decoder

Multiplexor Multiplexor A selector The output is selected by an input control

Implementation of a Multiplexor

n-input Multiplexor A Multiplexor can have n-inputs Require selective inputs Implementation of an n-input Multiplexor

Two-level Logic Try to Remember: Any Boolean Logic function can be implemented with only NOT, AND, OR functions We can also find that all logic functions can be written in a canonical form Sum of Product Logical Sum (OR) of terms joined by Product (AND) Product of Sum Logical Product (AND) of terms joined by Sum (OR)

Example Consider the following sum of products: Show the equivalent product of sums is:

In Class Exercise Considering the following truth table for D, write the function of D using sum of products

Answer Combinations that D is 1 Answer

Programmable Logic Array Programmable Logic Array (PLA) Two stages of logic An array of AND gates (product terms) An array of OR gates

PLA Example Considering the following table, implement the PLA for D, E, F

Another PLA Representation Dot in the AND plane Input, or its inverse, occurs in the product term Dot in the OR plane Corresponding product term appears in the corresponding output

Read Only Memory Read Only Memory (ROM) Programmable ROM (PROM) Has a set of locations that can be read Contents of these locations are fixed Programmable ROM (PROM) Can be burnt using a device called a “ROM programmer” Erasable Programmable Read Only Memory (EPROM) Data in the ROM can be deleted under ultra-violet rays EEPROM (Electrically Erasable Read Only Memory) Data in the ROM can be erased by a simple electric current

ROM Height Width mxn is the shape of the ROM m inputs 2m addressable entries (input lines) Width n outputs (functions) 2n output bits mxn is the shape of the ROM

ROMs and PLAs PLA is partially decoded ROM is fully decoded Contains a full output word for every possible input combination Always contain more entries than PLA PLA (7 entries) ROM (8 entries – 1 unused)

Don’t Care Don’t Care Output Don’t Care Input Don’t Care We don’t care about the actual values Output Don’t Care We don’t care about the value of an output for some input combination Input Don’t Care An output only depends on some of the inputs Advantages of Don’t Care Easier to optimize the implementation of a logic function

Example of Don’t Cares Original Truth Table

Example of Don’t Cares Output Don’t Cares Input Don’t Cares

Array of Logic Elements Bus In logic design, a collection of data lines that is treated together as a single logical signal Shared collection of lines with multiple sources 32-bit wide 2-to-1 multiplexor

What I want you to do Review Chapter 1 Review Appendix B