Fujitsu M304X Series Oem Manual page 79

Transmitted Data (TD)
universal synchronous
transmitter/receiver (T/R).
and are also connected to USART
The USART transmit/receive request line (IRQ)
microprocessor (MPU) via &bit
address lines are also connected to the interface buffer and internal bus MPU.
The interface MPU operation is controlled by microprograms stored in the ROM.
Microprogram execution
When one-word data is generated in the USART
issues a receive request interrupt to the interface MPU.
command. If not, the interface MPU stacks the data in the interface buffer.
If so, it responds with the printer status.
Transmitting data
When data transmission is necessary (for the printer status reponse,
transmission, or local loopback
writes data in the USART
interrupt.
When writing data into the interface buffer begins, the!
a control code or control sequence written in the interface buffer and
decodes it, than issues a command to the internal bus MPU.
Whether the command sent from the internal bus MFU terminates or not, if a
mechanical error or operator intervention request (indicated by the
Intervention Required
If the command termibates
command.
If printer operation is stopped due to a mechanical error or an operator
request (the internal bus MPU cannot operate in this state), the
interface MPU stops issuing the next command to the internal MPU and stops
reading data in the interface buffer until the mechanical error is corrected
or the operator intervention request ends.
The amount of data transmitted from the host can be reduced by the Repeat
Character command or the Move
Tabulation (HT) code using horizontal tab stop data downloaded by the Load
Horizontal Tab Stop Data command.
A line feed pitch of 6/8 lpi can be selected by the Select Vertical Pitch
command. A half-line feed pitch of 12 lpi can also be selected by using the
Half Line Feed command.
Responding to the Status Request command from the host, the printer reports its
status
and Received Data (RD)
asynchronous
The Data Terminal Ready (DTR), Request to Send
through the T/R.
bus lines and address lines.
is described
test), the interface MPU USART
every time the LJSART issues a transmit request
signal) occurs, it is reported to the interface MPU.
normally, the interface MPIJ
Horizontal Position command or by the Horizontal
response).
lines are connected to the
receiver/transmitter
is connected to
below.
from the serially sent data, the
through a
the interface
The bus and
The interface
data and
interface MPU detects
issues the next
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