M200 interfacing

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Sun Dec 29 15:51:00 2002

> > Why not just read two columns, each of which is twelve bits, pass that as
> > three bytes of raw binary, and then decode in the host machine?

On Sun, 29 Dec 2002, Ben Franchuk wrote:
> I would read all 80 columns

Of course. If there is a data communications bottleneck, trailing blanks
could be inferred, rather than explicitly transmitted from the reader to
the host machine, but ALL columns must be read.

> 16 bits each.

Why 16 bits? There are 12 physical bits present. (Y,X,0-9)
Or is that just for the convenience of doing it in 16 bit machines?
> Remember often a blank column could be read
> as a leading zero. One place to look for card
> to ascii? encoding is old data books on mask
> programable roms as that was a common use for
> them.

Decoding is the only part that remains truly trivial (in software). Even
a hardware based decoding could be done fairly easily with a ROM and using
the 12 bits to find the appropriate value in an array of 4096 possible
outputs.
Received on Sun Dec 29 2002 - 15:51:00 GMT