Logic Flow Diagram - Centronics 101 Technical Manual

Figure 1-1. MODEL 101 PRINTER (FRONT COVER REMOVED)
1.2 LOGIC FLOW DIAGRAM (FIGURE 1-2)
The standard printer contains a 132-character buffer. For serial data inputs, optional serial
interfaces allow data to be received at rates from 100 to 9600 baud. Several other optional inter-
faces are available as required by the user ..
Once a line of printable characters is stored in the buffer, head motion is initiated by act-
ivating the forward clutch, causing the print head to move from left to right across the paper. With
the head in motion, data is transmitted from the buffer to the character generator. From there,
character write pulses are sent to the driver circuits, which energize the print head solenoids causing
the print wires to form the characters on the paper.
Paper movement is initiated by a line feed, vertical tab or form feed function. Vertical
forms movement is hardware - controlled by a vertical format unit (VFU) which controls vertical
spacing by monitoring two channels in .
.a
punched paper tape.
I n addition, the printer recognizes the following special control codes: bell, delete and
elongated character, as described in Section 1.3.3.
Rev.G
1-2