TFLA-16 can be used with the TFLA-01 interface circuit, but the upper
eight channels will be duplicates of the lower eight.

Intended usage is with the OmberTech Logic Visualiser, using a buffered
LPT cable as described in page one of "tfla-16.pdf". Vcc should be
connected to the Logic Visualiser's 5V supply, or to an unused USB or
joystick port.

Information on the Logic Visualiser circuit design is available here:
http://computernerdkev.heliohost.org/logicvis/

Page two of "tfla-16.pdf" describes a simple circuit for connecting
sixteen inputs to the parallel port without a Logic Visualiser board.
Vcc should be connected to a 5V supply such as an unused USB or
joystick port. Model 74HC573 ICs can be used for IC1 and IC2 for
CMOS input logic level compatibility instead of TTL.

Page three shows how the circuits are wired to the DB25 plug. The
Logic Visualiser circuit sits "inline" between the DB25 plugs of
the cable. The input and output pin locations are therefore the
same on their respective connectors. LPT SELECT connects with
the standard /STROBE pin (pin 1). Pin numbers are normally written
on the face of the DB25 connector.
