IBM RT Series Hardware Reference Manual page 414

The following is a block diagram of the printer adapter portion of
the Monochrome Display and Printer Adapter.
8
25-Pin D-Shell
~
Connector
Bus BUffe-..,;r
8~1---1
..... Data Latc ...
h_...e-;8~-4."
~ ~
~
Enable
~
Clock
Trans-
1oIIII ...
~8:...
.......
-+ ____ ......
ceiver ...... ...
------...
r
DIR
Reset
DIR
~
Read
Data
Write Data
O.C.
Drivers
Command
I--------+-.....J
Decoder Write Control
Read Status
Read
Control
~
Bus Control
Buffers Latch
~
Enable
t..2...
L.....
fP"" ------...
Clock
~
..
...
5
... ...
'----t
Enable
,....... Clear
Printer Adapter Block Diagram
12 Monochrome Adapter
FDXT
INIT
PE
ACK
BUSY