Atari SLM-804 Service Manual

13
April 1988
2
THE SCOPE OF THIS
DOCUMENT
is
limited to
a
description
of the
Atari
Page Printer Interface host adapter hardware
and software system-level interface. This
document does not
provide information on the controller
to
printer engine
device-level interface.
1
.
Introduction
The Atari Page Printer Controller functions as
a
trans-
lator
between the parallel DMA
bus
interface (aka the Atari
Computer System Interface)
of the
Atari
ST
and the serial
video interface
of the
xerographic printer engine. The page
printer
controller
is
intelligent, providing device-
independent command interpretation and control
of
printer
operations. The
following
is
a
simplified block diagram
of
the Atari Page Printer Controller.
ATARI PAGE PRINTER CONTROLLER
DATA
<
—
Horiz Sync
I I
Video Data >
I
I
<
—
Video Clock
—
>
i I
<-- Print
Ready
I
Vert Sync >
I
Command
>
I
<
—
Status
I
MCU
CONTROL
Bus
communication follows
a
defined host-initiated dia-
log sequence consisting of
a
COMMAND PHASE, DATA OUT PHASE,
and STATUS PHASE. Data transfers are asynchronous and
fol-
low
a
Data Request
/
Acknowledge handshake protocol, with
one byte
of
data tranf erred during each handshake.
Please note that the controller contains
a
two-byte
FIFO which
is
loaded prior to the transfer
of
a
new block of
data
.
The host can interrogate the controller for
a
list of
configuration parameters which
is
received
during
an
EXTENDED STATUS
PHASE. The host can also send the con-
troller
a
parameter list during an
EXTENDED COMMAND
PHASE.
The Atari Corporation