SLIDE 1
Last week Processor (CPU) made of millions of transistors - - PDF document
Last week Processor (CPU) made of millions of transistors - - PDF document
10/19/2009 Last week Processor (CPU) made of millions of transistors Integrated circuits allow small powerful CPUs Control Unit, ALU, Registers, Bus, Cache Co- and multi-core processors Moores law: transistors on chip
SLIDE 2
SLIDE 3
10/19/2009 3
Transistors control electricity
Control current (0 or 1) via base
voltage (0 or 1)
An open transistor lets current flow
through
NPN: open only if base is on (1) PNP: open only if base is off (0)
Transistors control electricity
Control current (0 or 1) via base
voltage (0 or 1)
An open transistor lets current flow
through
NPN: open only if base is on (1) PNP: open only if base is off (0)
SLIDE 4
10/19/2009 4
Combining transistors
The NOT gate
Can build a NOT gate using 2
transistors
If A is 0 then X is 1 If A is 1 then X is 0
Combining transistors
The NOT gate
Can build a NOT gate using 2
transistors
If A is 0 then X is 1 If A is 1 then X is 0
SLIDE 5
10/19/2009 5
Combining transistors
The NOT gate
Can build a NOT gate using 2
transistors
If A is 0 then X is 1 If A is 1 then X is 0
Logic gates
NOT T gate
On only when input is off X = NOT A
SLIDE 6
10/19/2009 6
Logic gates
AND gate
On when both inputs are on X = AND A, B
Logic gates
OR gate
On when either input is on X = OR A, B
SLIDE 7
10/19/2009 7
Logic gates
NAND D gate
NOT AND: On unless both inputs are on X = NAND A, B
Logic gates
NOR gate
NOT OR: On when neither input is on X = NOR A, B
SLIDE 8
10/19/2009 8
Logic gates
XOR gate
Exclusive OR: On when only one input
is on
X = XOR A, B
Logic gates
XNOR OR gate
Exclusive NOT OR: On when both
inputs equal
X = XNOR A, B
SLIDE 9
10/19/2009 9
Logic gates
The NAND gate Not
- t in the exam
Buildi ding g a NA NAND
Can build a NAND gate using 4
transistors
SLIDE 10
10/19/2009 10
The NAND gate Not
- t in the exam
Buildi ding ng a NAND
Can build a NAND gate using 4
transistors
The NAND gate Not
- t in the exam
Building lding a NAND
Can build a NAND gate using 4
transistors
SLIDE 11
10/19/2009 11
The NAND gate Not
- t in the exam
Building lding a NAND
Can build a NAND gate using 4
transistors
The NAND gate Not
- t in the exam
Building lding a NAND
Can build a NAND gate using 4
transistors
SLIDE 12
10/19/2009 12
The NAND gate
Funct ction ional al Comp mplet eten eness ess
Can build a NAND gate using 4 transistors NAND & NOR are simplest 2-input gates NAND is functionally complete (so is NOR) It can be used to build all the other gates e.g. an AND gate In practice, processors contain just NAND
gates
The NAND gate
Funct ction ional al Comp mplet eten eness ess
NOT A = NAND A, A AND A, B = NOT (NAND A, B) OR A, B = NAND (NOT A), (NOT B) XOR A, B = OR (AND (NOT A), B), (AND A (NOT B))
SLIDE 13
10/19/2009 13
Digital circuits
The Half Ad Adder er
Adds two bits (A and B) together (sum S) Carry bit (C) indicates if sum is more
than one bit
Digital circuits
The Half Ad Adder
Sum S = XOR A, B Carry C = AND A, B
SLIDE 14
10/19/2009 14
Digital circuits
The Full Ad Adder
When adding
column of binary digits may get a carry bit from the previous column
Adds together two
bits (A and B) and a carry in bit C1
Carry-out C2
indicates if sum is more than one bit
Digital circuits Not
- t in the exam
The Full Ad Adder
Sum S = XOR (XOR A, B), C Carry-out C2 = OR (AND A, B), (AND C1, (XOR A, B))
SLIDE 15
10/19/2009 15
Digital circuits
Arithm thmetic etic-Log
- gic
c Unit (ALU)
ALU contains circuits for different
- perations
Arithmetic operations Addition (Full adder for each binary column) Subtraction, multiplication, division Logical operations AND, OR, NOT, ... Bitwise operations Shifts, rotations
Summary
Logic gates are built out of transistors There are many different logic gates NAND is functionally complete Digital circuits process data using gates Half and full adder Reading: Brookshear §1.1, White p.68-
69
http://en.wikipedia.org/wiki/Logic_gate