🚀 go-pugleaf

In article <2s0qek$8r0@nntp2.Stanford.EDU>, blakely@leland.Stanford.EDU (Bruce T. Blakely) writes:
>We have an instrument (a luminometer) that, acccording to the manual, has
>a "BCD signal output suitable for interface with Apple II and other 
>compatible data systems." The connector for this output is a Centronics
>style connector. However, we do not have an Apple II.
>
>Is there any (fairly simple) way that we can feed this BCD signal into
>a computer? 

BCD stands for binary coded decimal. 4 wires (bits) on the connector are used
to encode each decimal digit output. It was a handy interface back in the
days of nixie tubes and roll-your-own LED displays. An output value of, say,
255 was represented as 0011 0101 0101 (12 bits, 4 per digit).

>
>The machine also has an analogue output, for what its worth...
>

It wouldn't be hard to write a BCD-to-serial translator on a little
Motorola 'HC11 board or similar, as long as you know the pinouts on
the Centronics connector and as long as they're TTL so you don't have
to build a zillion level shifters. But since your sensor is most
likely an analog device with an analog output, imho you'd have
an easier time going into an A-D convertor on your Mac. If the 
output of the luminometer changes slowly as a function of time,
you can get by with one of the <$300 A-D convertors that plugs
into the serial port of the Mac.

Good luck.


Cedric Walker
Tulane University
New Orleans, LA