29 Dec
2002
29 Dec
'02
3:51 p.m.
> 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.