Motorola M6800 User Manual
Page 20
MPU-20
Number Systems
Everyone is quite familiar with the base 10 number system i.e. 0, 1,
2, 3, 4, 5, 6, 7, 8, & 9, since this is the system we all use day to day. Let
us review a typical number, say 2743, and see what it really means. The least
significant digit (LSD) is 3 and the most significant digit (MSD) is 2. Since
we are talking about a base 10 number, the number 2743 really is
= 3x100 + 4x101 + 7x102 + 2x103
= 3x1 + 4x10 + 7x100 + 2x1000
= 3 + 40 + 700 + 2000
= 2743.
In digital computers, base 10 numbers are represented in binary
form, i.e. 1's & 0's. Lets take a base 10 number and convert it to a binary
(base 2) number. A method of doing this is known as "repeated division by ?".
The base 10 number of 47 is converted to binary as shown below:
23
2 47
R=1
11
2 23
R=1
5
2 11
R=1
2
2 5
R=1
1011112
2
2 2
R=0
0
2 1
R=1
Converting 1011112 back to our base 10 number is done in the same
manner as above