Table of Contents
Advertisement
1.17:
TTL PARALLEL INTERFACE
A TTL parallel interface is standard and is mounted on the logic board. It is compatible
with most systems which have been designed to operate with Centronics printers. Certain
signals found on early Centronics printers are not provided. Should any problems with
compatibility arise, contact place of purchase.
The interface functions by accepting a 7-bit character code when a datastrobe transistions
from high-low, to low-high. Upon acceptance of the character, the acknowledge signal is
pulsed low for a short period of time. The host uses this as an indication that the character
has been received, and that another may be sent. During certain nonprinting intervals, such
as when paper is in motion, the busy signal is also raised to a high level. See Table 1-3 for
a complete description of the pin configuration.
1-9
Advertisement
Table of Contents
