Centronics Printer Interface
USING THE PRINTER PORT
Physical access to the printer port may be gained through connector
J6, a 20-pin header located behind connectors J2 and J3 at the
frontplane. An optional cable, the ZT 90039, is available from Ziatech
for transition from this 20-pin header to a 25-pin D-type connector
similar to that used by IBM for their printer cable. Connection to a
printer may be made by attaching the ZT 90039 to the IBM cable,
which then connects to the printer.
There are two methods by which STD DOS allows printing. The first
is used in the DOS command line in order to print a file or the
contents of the display. Typing
PRINT <filename>
sends a file to the
printer. To print the contents of the display, you must first write the
display contents to a file, then print that file. STD DOS does not
support the Print Screen utility that prints the display contents from a
keystroke on the keyboard.
The second method of printing is from within an application. For
details on this and the Print command, refer to your STD DOS system
manual and the IBM DOS Reference Manual.
If STD DOS is installed on the ZT 8809A, most of the printer port
signals are free for use by applications programs for general purpose
TTL I/O signals as long as no DOS print commands are executed by
the program. Direct access to this port from the program is available
at the appropriate addresses defined in the following sections of this
chapter.
If STD DOS is not installed, the port remains free for use by an
application’s code. The STD ROM Development System does not
initialize or use this port.
Three of the signals (SLIN*, INIT*, and AFD*) in the printer’s
Control Port register and one signal (ERR*) in the Status Port register
are used by STD DOS for alternate uses. These alternate uses may be
disabled by jumpers W37, W39, W46, W62, and W67 described in
Appendix A. If you are using STD DOS and the printer port, refer to
the discussions on pages 9-7 and 9-8 regarding the Control Port
register and the Status Port register.
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