2. History
• Vending machine became popular during the
industrial revolution .
• The first modern coin-operated vending
machines were introduced in England in the
early 1880s .
• The first vending machine in the U.S. was built
in 1888 by the Thomas Adams Gum
Company.
3. • In 1897 games has been added to these
machine .
• In December 1970, Ussery Industries of
Dallas, Texas at its Dallas convention displayed
its "talking" vending machine, the Venda
Talker.
4. What is the vending machine
• Electronic machine used to disperse a product to a
consumer after a certain amount of money has been
put into the machine.
• Vending machines are commonly used to disperse
beverages and snack items, but in recent
years companies have introduced vending machines
that disperse other items, even including electronic
items such as digital cameras or iPods.
5. Simple vending machine
The vending machine delivers an item after it
has received 15 cents in coins.
The machine has a single coin slot that accepts
nickels and dimes, one coin at a time.
A mechanical sensor indicates whether a dime
or a nickel has been inserted into the coin slot.
The controller's output causes a single item to
be released down a chute to the customer.
7. assume that N is asserted for one clock period
when a nickel is inserted into the coin slot and
that D is asserted when a dime has been
deposited.
Furthermore, we'll postulate that it is enough if
the machine asserts Open for one clock period
to release an item after 15 cents (or more) has
been deposited since the last reset.
8. Abstract representations
• Three nickels in sequence: N, N, N
• Two nickels followed by a dime: N, N, D
• A nickel followed by a dime: N, D
• A dime followed by a nickel: D, N
• Two dimes in sequence: D, D
10. The machine will pass through the states S0, S1,
S3, S7 if the input sequence is three nickels.
in state S0 if neither input N or D is asserted, we
assume the machine remains in state S0 (the
specification allows us to assume that N and D
are never asserted at the same time).
Also, we include the output Open only in states
in which it is asserted. Open is implicitly
unasserted in any other state.
11. State Minimization
This nine-state description isn't the "best" possible.
For one thing, since states S4, S5, S6,S7 and S8
have identical behavior, they can be combined
into a single state.
To reduce the number of states even further, we
can think of each state as representing the
amount of money received so far. For example, it
shouldn't matter whether the state representing
10 cents was reached through two nickels or one
dime.
16. Vending machine kinds
There are so many types of vending machines available
from different vending machine manufacturers and
suppliers.
Some machines need electricity to vend the products,
while some others use mechanical motion to vend.
They come in several sizes, shapes, colors, and prices.
Vending machines are found mostly in shopping
malls, waiting areas, bowling alleys, businesses, and
schools.
17. Commonly vending machines
• Soda vending machine
• Gumball vending machine
• Snack vending machine
• Food and toy vending machine
• Coffee vending machine
• Cigarette vending machines
• Pop corn vending machine
26. Present state Input Next state Output
QA QB N D DA DB C
0 0 0 0 0 0 0
0 0 0 1 1 0 0
0 0 1 0 0 1 0
0 0 1 1 X X 0
0 1 0 0 0 1 0
0 1 0 1 1 1 0
0 1 1 0 1 0 0
0 1 1 1 X X 0
1 0 0 0 1 0 0
1 0 0 1 1 1 0
1 0 1 0 1 1 0
1 0 1 1 X X 0
1 1 0 0 1 1 1
1 1 0 1 1 1 1
1 1 1 0 1 1 1
1 1 1 1 X X 1
27. DA 00 01 11 10
00 1 1
01 1 1 1 1
11 X X X X
10 1 1 1
C 00 01 11 10
00 1
01 1
11 1
10 1
DB 00 01 11 10
00 1 1
01 1 1 1
11 X X X X
10 1 1 1
QA QB QA AB
QA QB
N
D
N
D
N
D
28. Flip-flop Inputs Equations and System Output
Equation and it’s conversion to NAND Gates:
• DA = QA + D + NQB
= (QA + D + NQB)”
= (QA’D’(NQB)’)’
• DB = NQB’ + NQA + DQA + N’QB
= (NQB’ + NQA + DQA + N’QB)”
= ((NQB’)’(NQA)’(DQA)’(N’QB)’)’
• C’ = (QAQB)’
= ((QAQB)’)”
= (QA’QB’)’
