As I mnentioend the other night, I've added the parallel printer port to
that TD1100 viewdata terminal. The output is a DA15 socket, and in fact
the hardest part of adding the port was cutting the back panel of the
unit ot allow the conenctor to come through. I had to remove the back
panel entirely from the PCB, which invovled desoldering the line wires
and the mains wiring....
Anyway. I then had to make a cable from the DA15 to a 36 pin Microribbon
conenctor to conenct ot a Cnetronics-interfaced printer. As I mentioend,
I'd gueessed as to what the signals were, so I sued those guesses for the
initial wiring.
Connected the unit to an old Epson FX80+ and pressed the 'print' key on
the terminal. It printed. Some garbage, some readable text. I then
rememebred the pritner setup screen (type 'P#' at the dialer screen) and
found it was set to 'teletext compatible' -- i.e. it would handle the
various teletxt/viewdata controll codes and graphics. I reset it to
'ASCII text' and tried again. This time it printed correctly -- almsot.
It was double-spacign the lines.
I then realsied that the pritner had previously been used with a BBC
micro, a machine that, by default, sends only a <CR> as a newline.
There's a DIP swithc in most old Epsons to cater for this, it foces the
AutoFeedXT line on the inteface conenctor low. Only problem was, I didn't
haev the printer manaul.
Oh well, I just took it apart and traced the conenctions from the
AutoFeedXT pin through the filter resistor to a DRIP swithc. Turnrf it
off (so it no longer asserted the AutoFeedXT signal) and put the pritner
together. This time it worked fine. My gueses on the printer port signals
had probed to be correct.
In case anyoen else wants to do it, here's the wirelist (and colours) of
the cable I made :
1 o----D3------Or----o 5
2 o----D6------Bu----o 8
3 o----D7------Pu----o 9
4 o----D0------Bk----o 2
5 o----D4------Y-----o 6
6 o----D5------Gn----o 7
7 o----Err/----R/Bu--o 32
8 o----Gnd-----Gy----o 19
9 o----Gnd-----W-----o 30
10 o----D1------Be----o 3
11 o----D2------R-----o 4
12 o----Init/---Tq----o 31
13 o----Stb/----Pk----o 1
14 o----Ack/----R/Y---o 10
15 o----Busy----R/Gn--o 11
DA15P 36 pin Microribbon
-tony
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