PC Hardware A Beginner’s Guide

(^418) PC Hardware: A Beginner’s Guide
the source of its instructions. If the buffer fills up, the printer tells the computer to stop
sending data; when space is once again available in the buffer, the computer is sent the
signal to resume transmitting data. The printer reading data and sending instructions to
the printhead creates space in the buffer.
As the printer reads data from the print buffer, the data is decompressed and passed
to the printer’s controller. The controller interprets the print data and sends instructions to
the printhead and the inkjet nozzles as to when to print and which colors to use.
The nozzles on the printhead are very small. In fact, there is a block with dozens of
nozzles for each of the CMYK colors. Some printers use more nozzles per color. The
Epson Stylus Pro 5000, for example, uses 64 nozzles for each of the CMYK colors.
The controller interprets the data from the bitmap file for one pass of the printhead.
When a certain color is called for, a signal is sent to the printhead to fire that color’s nozzle
Figure 17-11. The 17 halftone dot possibilities using a 4 x 4 halftone cell