Printronix P9012, Maintenance Manual

Page: 56 / 256

2–38 Principles of Operation
Normal Operation
(Figure 2–29)
Character Printing
During one cycle of normal operation, the printer is set up and put online by
the operator, using the control panel. Host computer data is then read into the
data input buffer. ASCII data from the input buffer is compared to tables
stored in memory to determine the matrix locations to be printed for each
character and build the dot image buffer. Information from the dot image
buffer is synchronized with printer requirements using the magnetic pickup
signal then shifted out to hammer drivers. The selected hammers are fired.
When all dots in a row are printed, the paper is shifted one dot row and the
next dot row of data from the dot image buffer is synchronized then shifted
out to the hammer driver. Shifting of paper is delayed to allow double
printing when adjacent dot printing is required.
Self–Test
During self–test, internally generated data is used to build the dot image
buffer. Operation then proceeds as in normal printing.