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shirsch
November 22nd, 2015, 12:30 PM
I picked up one of these units on eBay recently. It's operational, but relies on an external printer to record status from each test. Some information is available on the alphanumeric display, but I'd really like to get either a printer or another computer connected to grab everything. The connector is a 20-pin 0.1" DIP header on the rear, obviously not a PC standard. By poking at it with an ohmmeter, I've concluded that it's probably a parallel port and have located what I believe to be the 8 data bits. That's where I'm stuck. There are at least two other lines connected to logic (they show a junction drop on my Fluke meter), but I'm not clear which is Busy and which is Strobe. Should a parallel port continue to output data when Busy is held low, or does it need to toggle state as it sees Strobe toggling? Any hints to getting this untangled?

Better yet, anyone on the forum own one of these beasts?

Gerardcjat
November 23rd, 2015, 07:22 AM
IF it is a 723,
you should have a look here ( Operation and Use ) :
http://www.dvq.com/docs/brian_inst/BrianInstrumentsManuals.pdf

shirsch
November 23rd, 2015, 08:06 AM
It is a 723 and I already have that manual. It provides absolutely no information on the printer interface - at least not that I could find. Are you seeing something relevant there?

shirsch
November 30th, 2015, 05:38 AM
With a little patience, PCB tracing and some pondering of logic analyzer captures I have the printer working.

Pinout for attached printer (20 pin DIP header on rear)

NOTE: Centronics parallel standard

1 Gnd
2 n/c
3 +15V Reg
4 Gnd
5 D6
6 D5
7 D4
8 D3
9 D2
10 D1
11 D0
12 Gnd
13 Strobe* (Out)
14 Gnd
15 Gnd
16 Gnd
17 n/c
18 n/c
19 Busy (In)
20 Gnd