binary means of two states. electricity can flow or not. current can be on or off. current on represents true. current off represents false. or current on represents 1 and current off represents 0. it could have been apple and pears
The Transistor as foundation
a transistor is an electronic component. it acts as switch. but the difference is that it is controlled by electricity. so, it can be switched on and off quickly
----- metal piece
●——- |——-●
-/-/-/ here acts as magnet
if you did physics, you might remember that magnetic fields are formed around any wire carrying current and coiling the wires acts as a magnet so when current is applied, the magnet is activated, attracting the metal piece, closing the switch, and current flows from the two ends ● ● summary : a transistor is used as a switch —
Logic gates logic gates form the foundation of computers, a gate is no wizardry. just arrangement of switches
the 3 basic gates are : AND OR and NOT gates
AND gate
an AND gate checks if both conditions are true for outputting true just like if x==4 and y==2 do …. it is constructed by placing 2 transistors in series
1 2
a●———-●__●———●b
| |
current will only flow from a to b if transistor / switch 1 and switch 2 is closed
OR gate
an or gate gives out true if one condition is true it is constructed by using 2 transistors in parallel
| 1
●————-●
a| |b
●————-●
| 2
transistor 1 and 2
if both open -> current flows
if one open one close -> current flows
if both closed -> no current
NOT gate
a not gate just outputs the opposite of the input
output
|
|
current ——●————–●—–ground
| input
when input is on / current flows, it opens the switch and current flows to ground i.e if input 1 -> no output and so 0
if no input so the switch is closed, and current deviates to output input 0 output 1 such is the NOT gate
XOR gate
a xor gate is as follows where a and b are inputs
a b output
1 1 0
1 0 1
0 1 1
0 0 0
it is constructed as follows
testing the first case of 1 1
see a XOR gate is nice !
try as an exercise the other inputs
the symbol of a XOR gate is
besides these gates, there are more !
On the naming of gates
they are called gates as they control current flow just like real gates control crowd flow