Twinaxial Printer Attachment; Port Control Logic; Receive Data Multiplexor; Serdes - IBM 5280 Technical Newsletter

TWINAXIAL PRINTER ATTACHMENT
The twinaxial printer attachment consists of the twinaxial
printer adapter and the twinaxial printer attachment MPU.
The twinaxial printer adapter controls the transfer of data
and commands to the printer as instructed by the twinaxial
printer attachment MPU. Printers are attached by twinaxial
cable to the twinaxial printer adapter.
The twinaxial printer adapter sends commands and data to
the printer and receives status iMormation from the printer
in a 16·bit frame. The 16·bit frame is described later in this
section (see 16-Bit Frame Concept).
Refer to logic diagram LD07 in the System Logic Manual
while you read the following description.
The components of the twinaxial printer adapter are as
follows:
• ' Driver/receivers (one for each port)
• Timing logic
I •
Port control logic
• Transmit data multiplex logic
• Receive data multiplex logic
• Serdes (serializer/deserializer)
• Control logic
Driver tReceivers
The driver/receivers provide the interface between the
twinaxial printer adapter and the twinaxial cable. One
driver/receiver circuit is provided for each port. In transmit
mode, the driver/receiver drives the twinaxial cable to the
printers with data to be transmitted. In receive mode, the
driver/receivers receive the data from the cable.
Timing Logic
The timing logic allows the attachment to synchronize with
the printer by generating a clocking signal from the received
data.
Port Control Logic
Page of SY31-0600-1
As updated
April 15, 1981
8y TN L SN20·9588
The port control logic provides the timing and control to
convert binary data to bi-phase data for transmit opera-
tions or to convert bi-phase data to binary data during
receive operations. This logic is driven by the 6 MHz
signal on the '+6 MHz' line.
Transmit Data Multiplexor
The transmit data multiplexor prepares the printer
adapter to transmit data by selecting the proper port
when a transmit command is ,issued by the twinaxial
printer attachment MPU.
Receive Data Multiplexor
The receive data multiplexor gates the adapter to receive
I data from the selected port when a receive command is
issued by the twinaxial printer attachment MPU .
Serdes
The serdes (serial/deserializer) accepts data from the 100
register and converts the data from parallel to serial. The
serdes also formats the data into a 16-bit frame by adding
the printer station address, parity bits and sync bits on the
data for transmission to the printer. The serdes converts
the serial data received from the printer to parallel data.
Control Logic
The control logic uses the adapter commands to determine
adapter functions. The logic provides adapter status and
control functions for the multiplexors and the serdes.
I
EXAMPLE OPERATION OF THE TWINAXIAL PRINTER
ATTACHMENT .
The following example shows how data is sent from main
storage to an attached printer:
1.
When the main MPU reads a printer write instruc-
tion, it places the instruction in the printer lOB and
turns on the attention line to the twinaxial printer
attachment MPU.
Printer Attachment
269