Hello Michael,

You could download an excellent tutorial on state machines
from AMD. Description of PAL programming for command by half steps
(8 steps by cycle) is given. Transposition of this sequence in 8051's code is
easy.

Don't forget timings. Stepping motors are slow devices, also
the 4 bits sequences must be writed with a sufficiently slow rate.
With interpreted MCSBASIC52, a FOR ... NEXT loop with 50 to 100
iterations is adequate, before the next 4 bits binary word.

Best regards,

J.M.