JUKI 6100 Technical Manual page 61

Once
the data
byte
has
been processed
by
the
MPU
the
BUSY
line
to the parallel
interface
is
dropped and
the
ACK
signal will
be sent to the
Host
CPU. The
Host
CPU may
now
initiate
another transfer
sequence by placing a
new
byte of data
on
the interface
and
sending the
STROBE
to the
printer.
The
entire operation,
from the reception of the strobe pulse to the transmission
of the
acknowledge
pulse, takes
approximately
two
milliseconds.
Maximum
data transfer rate
is
appro-
ximately
500
characters
per second.
ORIGIN/NAME
J02-1
STROBE
8155
PC.O A.
I
NT
8155
PC.1
A.BFR
MCU-1
BUSY
8051
P1.1
BUSY
8051
RD
8051 P1.2
ACK
J02-2
TO
J02-9
y
V
DATA
DESTINATION
8155
PC.2
8051 INTI
BUSY CKT
J02-1
BUSY CKT
8155
J02-10
8155
PORTA
Fig.
7.17
Data
transfer
sequence
between
MCU-1
and Host
CPU
The
Slave
Control Unit
(SCU-1 board) accepts
commands
from
the
MCU-1
board
and
translates
them
into control signals
which perform
the
mechanical
functions
necessary to print a character,
space
the carriage,
move
the forms,
etc.
The
main
component
of
the
SCU
is
a
microprocessor with an
internal
4K
ROM
which
contains the
program
for controlling the functions.
The
MPU
may
be
one
of
two
types,
an 8051
whose
control
program
is
in a
Masked
ROM
and
may
not be
altered,
or
an 8751 which
uses
an
EP-ROM.
The 8051 and 8751
are
operationally
identical
with
the
exception of
the
internal
ROM.
The
ports
of the
MPU
are
configured
as
follows:
Port 0
:
All bits set as
inputs for receiving control
signals
such
as
the carriage
home
pulse,
daisywheel sprocket
home, paper end (with
tractor feature),
etc.
Port
1
:
All
bits set as
outputs. Provides the actual clock pulses to the various
stepper
motor
driver circuitry.
Port 2
:
All bits set as
outputs. This port provides gating
signals
which
allow
vertical
forms motion, daisywheel
character selection, linear stepper
motion,
etc.
This port
also
provides the control
lines to
energize the
ribbon
clutch
and
fire
the
hammer
solenoid.
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