Epson FX-100 User Manual download pdf (Page 153)

Since computers use the binary numbering system (O

and 1s only),

it is most efficient for each pin to correspond to the decimal equivalent

of one bit in an &bit binary number: 1, 2, 4, 8, 16, etc. (see Figure

10-3).

Figure 10-3. Pins labelled uniquely

The hardware makes this the most practical labelling system. Each

pin corresponds to one of the eight data lines from the computer, and

each data line corresponds to one bit in a binary number. The place

values in a binary number are nothing more than the series made up of

powers of two. Figure 10-4 shows how you use a decimal sum--74--

to fire a particular pattern of pins.

If you try adding several sets of pins together, you’ll see that with

this system you get no duplicates. The number 6 represents pins 2 and

4 (since 2 + 4 = 6) and there is no other way to get 6 by adding

powers of two. This means that any combination of the eight pins

adds up to a unique decimal number which falls within the range 0 to

255.

136

1 2 ... 148 149 150 151 152 153 154 155 156 157 158 ... 267 268

No comments

Epson FX-100 User Manual Page 153