2. Fundamentals of Logic gates

2.1 LOGIC GATES

We have seen that the foundation of logic design is seated in a well defined axiomatic system called Boolean algebra, which was shown to be what is known as a “Huntington system”. In this axiomatic system the definition of AND and OR operators or functions was set forth and these were found to be well defined operators having certain properties that allow us to extend their definition to Hardware applications. These AND and OR operators, sometimes referred to as connectives, actually suggest a function that can be emulated by some H/w logic device. The logic Hardware devices just mentioned are commonly referred to as “gates”.

Keep in mind that the usage of “gate” refers to an actual piece of Hardware where “function” or “operation” refers to a logic operator AND. On the other hand, when we refer to a “gate” we are referring directly to a piece of hardware called a gate. The main point to remember is ‘Don’t confuse gates with logic operators’.

2.1.1 Basic Logic Gates

Positive and Negative Logic Designation

The binary signals at the inputs or outputs of any gate can have one of the two values except during transition. One signal levels represents logic 1 and the other logic 0. Since two signal values are assigned two to logic values, there exist two different assignments of signals to logic.

Logics 1 and 0 are generally represented by different voltage levels. Consider the two values of a binary signal as shown in Fig. 2.5.1. One value must be higher than the other since the two values must be different in order to distinguish between them. We designate the higher voltage level by H and lower voltage level by L. There are two choices for logic values assignment. Choosing the high-level (H) to represent logic 1 as shown in (a) defines a positive logic system. Choosing the low level L to represent logic-1 as shown in (b), defines a negative logic system.

Fig. 2.5.1

The terms positive and negative are somewhat misleading since both signal values may be positive or both may be negative. Therefore, it is not signal polarity that determines the type of logic, but rather the assignment of logic values according to the relative amplitudes of the signals.

The effect of changing from one logic designation to the other equivalent to complementing the logic functions because of the principle of duality of Boolean algebra.

Gate Definition

A ‘gate’ is defined as a multi-input (> 2) hardware device that has a two-level output. The output level (1–H/0–L) of the gate is a strict and repeatable function of the two-level (1–H/0–L) combinations applied to its inputs. Fig. 2.5.2 shows a general model of a gate.

Fig. 2.5.2 The general model of a gate.

The term “logic” is usually used to refer to a decision making process. A logic gate, then, is a circuit that can decide to say yes or no at the output based upon inputs. We apply voltage as the input to any gate, therefore the Boolean (logic) 0 and 1 do not represent actual number but instead represent the state of a voltage variable or what is called its logic level. Sometimes logic 0 and logic 1 may be called as shown in table below:

Table 2.5.2

a. OR Gate

The OR gate is sometimes called the “any or all gate”. To show the OR gate we use the logical symbol in Fig. 2.5.4(a).

b.c. Fig. 2.5.4 (a) OR gate logic symbol . (b) Practical OR gate circuit.d.e. A truth-table for the ‘OR’ gate is shown below according to Fig. 2.5.4(b). The truth-table lists

the switch and light conditions for the OR gate. The unique output from the OR gate is a LOW only when all inputs are low. The output column in Table (2.5.4) shows that only the first line generates a 0 while all others are 1.

Table 2.5.4

f.

g. Fig. 2.5.4(c) shows the ways to express that input A is ORed with input B to produce output Y.

h.i. Fig. 2.5.4 (c)

j. Example. Determine the output Y from the OR gate for the given input waveform shown in Fig. 2.5.4(d).

k.l. Fig. 2.5.4 (d)

m. Solution. The output of an OR gate is determined by realizing that it will be low only when both inputs are low at the same time. For the inputs the outputs is low only during period t2. In remaining time output is 1 as shown in Fig. 2.5.4(e).

n.o. Fig. 2.5.4 (e)

p. We are now familiar with AND and OR gates. At this stage, to illustrate at least in part how a word statement can be formulated into a mathematical statement (Boolean expression) and then to hardware network, consider the following example:

q. Example. Utkarsha will go to school if Anand and Sawan go to school, or Anand and Ayush go to school.

r. Solution. This statement can be symbolized as a Boolean expression as follows:

s.t. The next step is to transform this Boolean expression into a Hardware network and this is

where AND and OR gates are used.

u.v. The output of gate 1 is high only if both the inputs A and S are high (mean both Anandand

Sawan go to school). This is the first condition for Utkarsha to go to school.w. The output of gate 2 is high only if both the inputs A and A.Y are high (means both Anand and

Ayush go to school). This is the second condition for Utkarsha to go to school.x. According to example atleast one condition must be fullfilled in order that Utkarsha goesto

school. The output of gate 3 is high when any of the input to gate 3 is high means at leastone condition is fulfilled or both the inputs to gate 3 are high means both the conditions are fulfilled.

y. The example also demonstrates that Anand has to go to school in any condition otherwise Utkarsha will not go to school.

z.b. AND Gate

The AND gate is sometimes called the “all or nothing gate”. To show the AND gate we use the logic symbol in Fig. 2.5.3(a). This is the standard symbol to memorize and use from now on for AND gates.

Fig. 2.5.3 (a) AND Gate logic symbol. (b) Practical AND gate circuit.

Now, let us consider Fig. 2.5.3(b). The AND gate in this figure is connnected to input switches A and B. The output indicator is an LED. If a low voltage (Ground, GND) appears at inputs, A and B, then the output LED is not bit. This situation is illustrated in table (). Line 1 indicates that if the inputs are binary 0 and 0, then the output will be binary 0. Notice that only binary 1s at both A and B will produce a binary 1 at the output.

Table 2.5.3 AND Truth Table

It is a +5V compared to GND appearing at A, B, or Y that is called a binary 1 or a HIGH voltage.A binary 0, or Low voltage, is defined as a GND voltage (near 0V compared to GND) appearing at A, B or Y. We are using positive logic because it takes a positive +5V to produce what we call a binary 1.

The truth table is said to discribe the AND

function. The unique output from the AND gate is a HIGH only when all inputs are HIGH.

Fig. 2.5.3 (c) shows the ways to express

that input A is ANDed with input B to produce

output Y.

Pulsed Operation

In many applications, the inputs to a gate may be voltage that change with time between

the two logic levels and are called as pulsed waveforms. In studying the pulsed operation of an AND gate, we consider the inputs with respect to each other in order to determine the output level at any given time. Following example illustrates this operation:

Example. Determine the output Y from the AND gate for the given input waveform

shown in Fig. 2.5.3(d).

.

Fig. 2.5.3 (d)

Solution. The output of an AND gate is determined by realizing that it will be high only when both inputs are high at the same time. For the inputs the outputs is high only during t3 period. In remaining times, the outputs is 0 as shown in Fig. 2.5.3(e).

Fig. 2.5.3 (e)

Fig. 2.5.3 (e)

c. NOT Gate

In digital logic, an inverter or NOT gate is a logic gate which implements logical negation. The truth table is shown on the right.

This represents perfect switching behavior, which is the defining assumption in Digital electronics. In practice, actual devices have electrical characteristics that must be carefully considered when designing inverters. In fact, the non-ideal transition region behavior of a CMOS inverter makes it useful in analog electronics as a class A amplifier (e.g., as the output stage of an operational amplifier [1

NOT gates are often called inverters. A NOT gate's output signal is the opposite of its input signal. Note that the symbol of the NOT gate is the same as that of the buffer, except for the small circle near its output. Small circles at input or output lines of a gate's schematic symbol denote the fact that the signal is inverted.

Input Output   L        H  H         L

2.1.2 Universal Gates

NAND and NOR gates. The NAND and NOR gates are widely used and are readily available from most integrated circuit manufacturers. A major reason for the widespread use of these gates is that they are both UNIVERSAL gates, universal in the sense that both can be used for AND operators, OR operators, as well as Inverter. Thus, we see that a complex digital system can be completely synthesized using only NAND gates or NOR gates.

a. NAND GateThe NAND gate is a NOT AND, or an inverted AND function. The standard logic symbol for the NAND gate is shown in Fig. (2.5.7a). The little invert bubble (small circle) on the right end of the symbol means to invert the output of AND.

b.

Fig. 2.5.7 (a) NAND gate logic symbol (b) A Boolean expression for the output of a NAND gate.

Figure 2.5.7(b) shows a separate AND gate and inverter being used to produce the NAND logic function. Also notice that the Boolean expression for the AND gate, (A.B) and the NAND (A.B)are shown on the logic diagram of Fig. 2.5.7(b).

The truth-table for the NAND gate is shown in Fig. 2.5.7(c). The truth-table for the NAND gate is developed by inverting the output of the AND gate. ‘The unique output from the NAND gate is a LOW only when all inputs are HIGH.

c.d. Fig. 2.5.7 (c) Truth-table for AND and NAND gates.

Fig. 2.5.7 (d) shows the ways to express that input A is NANDed with input B yielding output Y.

e.f. Fig. 2.5.7 (d)

Example. Determine the output Y from the NAND gate from the given input waveform

shown in Fig. 2.6.7 (e).

g.h. Fig. 2.5.7 (e)

Solution. The output of NAND gate is determined by realizing that it will be low only

when both the inputs are high and in all other conditions it will be high. The ouput Y is

shown in Fig. 2.5.7(f).

i.j. Fig. 2.5.7 (f)

The NAND gate as a UNIVERSAL Gate

The chart in Fig. 2.5.7(g) shows how would you wire NAND gates to create any of the other basic logic functions. The logic function to be performed is listed in the left column of the table; the customary symbol for that function is listed in the center column. In the right column, is a symbol diagram of how NAND gates would be wired to perform the logic function.

k.l. Fig. 2.5.7 (g)

m. The NOR gate. The NOR gate is actually a NOT OR gate or an inverted OR function.n. The standard logic symbol for the NOR gate is shown in Fig. 2.5.7(h)

o.p. Fig. 2.5.7 (h) NOR gate logic symbol (i) Boolean expression for the output of NOR gate. Note

that the NOR symbol is an OR symbol with a small invert bubble on the right side. The NOR function is being performed by an OR gate and an inverter in Fig. 2.5.7(i). The Boolean function for the OR function is shown (A + B), the Boolean expression for the final NOR function is (A + B).

q. The truth-table for the NOR gate is shown in Fig. 2.5.7(j). Notice that the NOR gate truth table is just the complement of the output of the OR gate. The unique output from the NOR gate is a HIGH only when all inputs are LOW.

r.s. Fig. 2.5.7 (j) Truth-table for OR and NOR gates.

t. Figure 2.5.7(k) shows the ways to express that input A is ORed with input B yieldingu. output Y.

v.w.

x. Fig. 2.5.7 (k)y. Example. Determine the output Y from the NOR gate from the given input waveform shown

in Fig. 2.5.7(l).

z.aa. Fig. 2.5.7 (l)

bb. Solution. The output of NOR gate is determined by realizing that it will be HIGH only when both the inputs are LOW and in all other conditions it will be high. The output Y is shown in Fig. 2.5.7(m).

cc.

dd. Fig. 2.5.7 (m)

B . NOR Gate The NOR gate as a UNIVERSAL gate.

The chart in Fig. 2.5.7(n) shows how would your wire NOR gates to create any of the other basic logic functions.

Fig. 2.5.7 (n)

2.1.3 Coincidence gates

a. The Exclusive OR Gate

The exclusive OR gate is sometimes referred to as the “Odd but not the even gate”. It is often shortend as “XOR gate”. The logic diagram is shown in Fig. 2.5.8 (a) with its Boolean expression. The symbol means the terms are XORed together.

Fig. 2.5.8 (a)

The truth table for XOR gate is shown in Fig. 2.5.8 (b). Notice that if any but not all the inputs are 1, then the output will be 1. ‘The unique characteristic of the XOR gates that it produces a HIGH output only when the odd no. of HIGH inputs are present.’

Fig. 2.5.8 (b)

To demonstrate this, Fig. 2.5.8 (c) shows a three input XOR gate logic symbol and the truth table Fig. 2.5.8 (d). The Boolean expression for a three input XOR gate can be written as

Fig. 2.5.8 (c)

Fig. 2.5.8 (d)

Putting the value of X, we get

Y = (AB+ AB)C + (AB+ AB).C

Y = ABC+ ABC+ ABC + ABC

The HIGH outputs are generated only when odd number of HIGH inputs are present (see T.T.)

‘This is why XOR function is also known as odd function’.

Fig. 2.5.8 (e) shows the ways to express that input A is XORed with input B yielding

output Y.

Fig. 2.5.8 (e)

The XOR gate using AND OR-NOT gates.

we know A B = AB+ AB

As we know NAND and NOR are universal gates means any logic diagram can be made using only NAND gates or using only NOR gates.

XOR gate using NAND gates only.

XOR using NOR gates only. The procedure for implementing any logic function using only universal gate (only NAND gates or only NOR gates) will be treated in detail in section 2.6.

Example. Determine the output Y from the XOR gate from the given input waveform shown in Fig. 2.5.8 (f).

Fig. 2.5.8 (f)

Solution. The output XOR gate is determined by realizing that it will be HIGH only when the odd number of high inputs are present therefore the output Y is high for time period t2 and t5 as shown in Fig. 2.5.8 (g).

b. The Exclusive NOR gatec.d. The Exclusive NOR gate is sometimes reffered to as the ‘COINCIDENCE’ or ‘EQUIVALENCE’

gate. This is often shortened as ‘XNOR’ gate. The logic diagram is shown in Fig. 2.5.9 (a).

e.

f. Fig. 2.5.9 (a)g. Observe that it is the XOR symbol with the added invert bubble on the output side. The

Boolean expression for XNOR is therefore, the invert of XOR function denoted by symbol O.

h.i.j. The truth table for XNOR gate is shown in Fig. 2.5.9 (b).

k.l. Fig. 2.5.9 (b)

m. Notice that the output of XNOR gate is the complement of XOR truth table.n. ‘The unique output of the XNOR gate is a LOW only when an odd number of input are HIGH’.

o.p. Fig. 2.5.9 (c)

q.r. Fig. 2.5.9 (d)

s. To demonstrate this, Fig. 2.5.9 (c) shows a three input XNOR gate logic symbol and the truth-table 2.5.9 (d).

t. Figure 2.5.9 (e) shows the ways to express that input A is XNORed with input B yieldingu. output Y.

v.

w.x. Fig. 2.5.9 (e)

y. Now at this point, it is left as an exercise for the reader to make XNOR gate using ANDOR-NOT gates, using NAND gates only and using NOR gates only.

z. Example. Determine the output Y from the XNOR gate from the given input waveform shown in Fig. 2.5.9 (f).

aa.bb. Fig. 2.5.9 (f)

cc. Solution. The output of XNOR gate is determined by realizing that it will be HIGH only when the even-number of high inputs are present, therefore the output Y is high for time period t2 and t5 as shown in Fig. 2.5.9 (g).

dd.ee. F ig. 2.5.9 (g)

ff.a.The Exclusive NOR gate

The Exclusive NOR gate is sometimes reffered to as the ‘COINCIDENCE’ or ‘EQUIVALENCE’ gate. This is often shortened as ‘XNOR’ gate. The logic diagram is shown in Fig. 2.5.9 (a).

gg.hh. Fig. 2.5.9 (a)

ii. Observe that it is the XOR symbol with the added invert bubble on the output side. The Boolean expression for XNOR is therefore, the invert of XOR function denoted by symbol O.

jj.kk.ll. The truth table for XNOR gate is shown in Fig. 2.5.9 (b).

mm.nn. Fig. 2.5.9 (b)

oo. Notice that the output of XNOR gate is the complement of XOR truth table.pp. ‘The unique output of the XNOR gate is a LOW only when an odd number of input are HIGH’.

qq.rr. Fig. 2.5.9 (c)

ss.tt. Fig. 2.5.9 (d)

uu. To demonstrate this, Fig. 2.5.9 (c) shows a three input XNOR gate logic symbol and the truth-table 2.5.9 (d).

vv. Figure 2.5.9 (e) shows the ways to express that input A is XNORed with input B yieldingww. output Y.xx.

yy.zz. Fig. 2.5.9 (e)

aaa. Now at this point, it is left as an exercise for the reader to make XNOR gate using ANDOR-NOT gates, using NAND gates only and using NOR gates only.

bbb. Example. Determine the output Y from the XNOR gate from the given input waveform shown in Fig. 2.5.9 (f).

ccc.ddd. Fig. 2.5.9 (f)

eee. Solution. The output of XNOR gate is determined by realizing that it will be HIGH only when the even-number of high inputs are present, therefore the output Y is high for time period t2 and t5 as shown in Fig. 2.5.9 (g).

fff.ggg. F ig. 2.5.9 (g)

hhh.

2.2 L OGIC DIAGRAM

Are diagrams in the field of logic, used for representation and to carry out certain types of reasoning.

Basic Logic Diagrams Basic  logic  diagrams  are  used  to  show  the operation of a particular unit or component. Basic logic symbols are shown in their proper relationship so as to show operation only in the most simplified form  possible.  Figure  6-24  shows  a  basic  logic diagram for a serial subtractor. The operation of the unit is described briefly in the next paragraph. In the basic subtractor in figure 6-24, assume you want to subtract binary 011 (decimal 1) from binary 100 (decimal 4). At time Io, the 0 input at A and 1 input at B of inhibitor I1 results in a 0 output from inhibitor I1 and a 1 output from inhibitor I2. The 0 output from I1 and the 1 output from I2 are applied to OR gate G1, producing a 1 output from G1. The 1 output from I2 is also applied to the delay line. The I output from G1 along with the 0 output from the delay line produces 1 output from I3. The 1 input from G1 and the 0 input from the delay line produce a 0 output from inhibitor I4. The 0 output from L and the 1 output from I3 are applied to OR gate G2 producing a 1 output.

At time t1 the 0 inputs on the A and B input lines of I1 produce 0 outputs from I1 and I2. The 0 inputs on both input lines of OR gate G1 result in a 0 output from G1. The I input applied to the delay line at time to emerges (1 bit time delay) and is now applied to the inhibit line of 13 producing an 0 output from I3. The 1 output from the delay line is also applied to inhibitor I4, and along with the 0 output from G1 produces a 1 output from I4. The I4 output is recycled back into the delay line, and also applied to OR gate G2. As a result of the 0 and 1 inputs from I3, and I4, OR gate G2 produces a 1 output. At time t2, the 1 input on the A line and the 0 input on the B line of I1 produce a 1 output from I1 and a 0 output from I2. These outputs applied to OR gate G1 produce a 1 output from G1, which is applied to 13 and I4. The delay line now produces a 1 output (recycled in at time t1), which is applied to I3 and I4. The 1 output from the delay line along with the 1 output from G1 produces a 0 output from I3. The 1 output from G1 along with the 1 output from the delay line produces a 0 output from I4. With 0 outputs from I3 and I4, OR gate G2 produces a 0 output.

   

 

 

2.3 Truth Table

A truth table shows how a logic circuit's output responds to various combinations of the inputs, using logic 1 for true and logic 0 for false. All permutations of the inputs are listed on the left, and the output of the circuit is listed on the right. The desired output can be achieved by a combination of logic gates. A truth table for two inputs is shown, but it can be extended to any number of inputs. The input columns are usually constructed in the order of binary counting with a number of bits equal to the number of inputs.

Truth table for most commonly used logical operators

Here is a truth table giving definitions of the most commonly used 7 of the 16 possible truth functions of 2 binary variables (P,Q are thus boolean variables):

P Q

T T T T F T T T T

T F F T T F F T F

F T F T T F T F F

F F F F F T T T T

Key:

T = true, F = false

= AND (logical conjunction)

= OR (logical disjunction)

= XOR (exclusive or)

= XNOR (exclusive nor)

= conditional "if-then"

= conditional "(then)-if"

biconditional or "if-and-only-if" is logically equivalent to : XNOR (exclusive nor).

Condensed truth tables for binary operators

For binary operators, a condensed form of truth table is also used, where the row headings and the column headings specify the operands and the table cells specify the result. For example Boolean logic uses this condensed truth table notation:

∧ F T

F F F

T F T

∨ F T

F F T

T T T

This notation is useful especially if the operations are commutative, although one can additionally specify that the rows are the first operand and the columns are the second operand. This condensed notation is particularly useful in discussing multi-valued extensions of logic, as it significantly cuts down on combinatoric explosion of the number of rows otherwise needed. It also provides for quickly recognizable characteristic "shape" of the distribution of the values in the table which can assist the reader in grasping the rules more quickly.

Truth tables in digital logic

Truth tables are also used to specify the functionality of hardware look-up tables (LUTs) in digital logic circuitry. For an n-input LUT, the truth table will have 2^n values (or rows in the above tabular format), completely specifying a boolean function for the LUT. By representing each boolean value as a bit in a binary number, truth table values can be efficiently encoded as integer values in electronic design automation (EDA) software. For example, a 32-bit integer can encode the truth table for a LUT with up to 5 inputs.

When using an integer representation of a truth table, the output value of the LUT can be obtained by calculating a bit index k based on the input values of the LUT, in which case the LUT's output value is the kth bit of the integer. For example, to evaluate the output value of a LUT given an array of n boolean input values, the bit index of the truth table's output value can be computed as follows: if the ith input is true, let Vi = 1, else let Vi = 0. Then the kth bit of the binary representation of the truth table is the LUT's output value, where k = V0*2^0 + V1*2^1 + V2*2^2 + ... + Vn*2^n.

Truth tables are a simple and straightforward way to encode boolean functions, however given the exponential growth in size as the number of inputs increase, they are not suitable for functions with a large number of inputs. Other representations which are more memory efficient are text equations and binary decision diagrams.

Applications of truth tables in digital electronics

In digital electronics (and computer science, fields of engineering derived from applied logic and math), truth tables can be used to reduce basic boolean operations to simple correlations of inputs to outputs, without the use of logic gates or code. For example, a binary addition can be represented with the truth table:

A B | C R1 1 | 1 01 0 | 0 10 1 | 0 10 0 | 0 0

where

A = First OperandB = Second OperandC = Carry R = Result

This truth table is read left to right:

Value pair (A,B) equals value pair (C,R). Or for this example, A plus B equal result R, with the Carry C.

Note that this table does not describe the logic operations necessary to implement this operation, rather it simply specifies the function of inputs to output values.

In this case it can only be used for very simple inputs and outputs, such as 1's and 0's, however if the number of types of values one can have on the inputs increases, the size of the truth table will increase.

For instance, in an addition operation, one needs two operands, A and B. Each can have one of two values, zero or one. The number of combinations of these two values is 2x2, or four. So the result is four possible outputs of C and R. If one was to use base 3, the size would increase to 3x3, or nine possible outputs.

The first "addition" example above is called a half-adder. A full-adder is when the carry from the previous operation is provided as input to the next adder. Thus, a truth table of eight rows would be needed to describe a full adder's logic:

A B C* | C R 0 0 0 | 0 0 0 1 0 | 0 11 0 0 | 0 11 1 0 | 1 00 0 1 | 0 10 1 1 | 1 01 0 1 | 1 01 1 1 | 1 1

Same as previous, but.. C* = Carry from previous adder

2.4 CIRCUIT MAKING

In order to play with TTL gates, you must have several pieces of equipment. Here's a list of what you will need to purchase:

A breadboard A volt-ohm meter (also known as a multimeter) A logic probe (optional) A regulated 5-volt power supply

A collection of TTL chips to experiment with Several LEDs (light emitting diodes) to see outputs of the gates Several resistors for the LEDs Some wire (20 to 28 gauge) to hook things together

These parts together might cost between $40 and $60 or so, depending on where you get them.

Let's walk through a few details on these parts to make you more familiar with them:

As described on the previous page, a breadboard is a device that makes it easy to wire up your circuits. A volt-ohm meter lets you measure voltage and current easily. We will use it to make sure that our power

supply is producing the right voltage. The logic probe is optional. It makes it easy to test the state (1 or 0) of a wire,

but you can do the same thing with an LED. Of the parts described above, all are easy except the 5-volt power supply. No

one seems to sell a simple, cheap 5-volt regulated power supply. You therefore have two choices. You can either buy a surplus power supply from Jameco (for something like a video game) and use the 5-volt supply from it, or you can use a little power-cube transformer and then build the regulator yourself. We will talk through both options below.

An LED (light emitting diode) is a mini light bulb. You use LEDs to see the output of a gate.

We will use the resistors to protect the LEDs. If you fail to use the resistors, the LEDs will burn out immediately.

This equipment is not the sort of stuff you are going to find at the corner store. However, it is not hard to obtain these parts. You have a few choices when trying to purchase the components listed above:

1. Radio Shack 2. A local electronics parts store - Most major cities have electronics parts stores, and many cities are blessed

with good surplus electronics stores. If you can find a good surplus store in your area that caters to people building their own stuff, then you have found a goldmine.

3. A mail-order house like Jameco - Jameco has been in business for decades, has a good inventory and good prices. (Be sure to download their PDF catalog or get a paper catalog from them -- it makes it much easier to traverse the Web site.)

The following table shows you what you need to buy, with Jameco part numbers listed.

Part Jameco #

Breadboard 20722

Volt-ohm meter 119212

Logic probe (optional) 149930

Regulated 5-volt power supply See below

7400 (NAND gates) 48979

7402 (NOR gates) 49015

7404 (NOT gates) 49040

A resistor and an LED

7408 (AND gates) 49146

7432 (OR gates) 50235

7486 (XOR gates) 50665

5 to 10 LEDs 94529*

5 to 10 330-ohm resistors 30867

Wire (20 to 28 gauge) 36767

For the Power Supply (optional)

(See next section for details)

Part Jameco #

Transformer (7 to 12 volts, 300ma) 149964

7805 5-volt voltage regulator (TO-220 case) 51262

2 470-microfarad electrolytic capacitors 93817