1. Computer Architecture & Operations I
Instructor: Ryan Florin

2. 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

3. 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

4. Decoder Example
3-8 Decoder

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

6. Implementation of a Multiplexor

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

8. 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)

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

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

11. Answer
Combinations that D is 1
Answer

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

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

15. 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

16. 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

17. 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

18. 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)

19. 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

20. Example of Don’t Cares
Original Truth Table

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

22. 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

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