In this case, each of the eight bits in a byte of data sent to the printer corresponds to one pin on the printhead. A bit’s value can be either 1 or 0. When the printer receives the data, it interprets a bit with a value of 1 as a command to fire the corresponding pin. Bits that are set to 0 don’t cause pins to fire.

Each block code will end up with its own “byte ID” so it can be visualized and identified on paper in the graphics line. But before getting there, a few tests have been done to try different bit combos and select the generators the most aesthetically pleasing for us :)

Below, one of the small quick and dirty shell scripts used to quickly test different patterns:

#!/bin/sh
# OKI 320 ML tests
# this test is to generate (crap) random 8 pin mode patterns
#PRNG
function rand {
echo "obase=8;`expr $RANDOM % 256`" | bc
}
function randpat {
n=1
while [ $n -le 256 ]; do
RND=`rand`
echo -ne '\'$RND
n=$((n+1))
done
}
PATTERN=`randpat`
# noise
# PATTERN2=`head /dev/urandom -c 1024`
echo -e '^[@^[5^[9^[*1\4'$PATTERN'^[@' | lp -o raw