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Commands
The numbers in parentheses are the bit configurations
that are in positions 7 through 14 of each command.
Activate Read (00000000) is inserted between a ' read
status' command and the data frame that follows it.
The 'activate read' command should be issued only after
a not-busy, no-exception, no-line-parity error response
is returned to a 'poll' command.
Activate Write (00000001) is inserted between a 'write
data' command and the data frame(s). This command
initiates the start of the data transfer that follows a
'write data' command. The 'activate write' command
should not be issued until a not-busy, no-exception,
no-line-parity error response is returned to a 'poll'
command.
Clear (0001 0010) is used to clear all printer buffers. No
forms motion results from this command. If the printer
is not ready, the Data Cleared light is turned on.
Pressing the Start switch turns the Data Cleared light
off.
.
EOO (01100010) designates the end of the command
queue. Only polls will be accepted until a not-busy
status is returned in response to a poll.
Poll (xxx 1 0000) is sent from the controller to the printer
to start the transfer of 2 status words per poll. At
power on time a single frame response is made until the
printer receives a 'set mode' command. The'bits in the
command modifier are:
7·
A reserved bit that is normally
o.
8
Acknowledges and resets the line parity error
response bit in the printer. This bit is effective
after a not- busy status is received from the
printer.
9
Acknowledges the last status transmission to allow
new status to be sent. If bit 9 is a 1, updated
responses are made when they are available. If bit
9 is a 0, the former response frames are resent
(except for real time status, which is always at the
latest level).
Read Status (1000 1000)· initiates the transfer from the
printer of one status word that contains information
about the condition of the printer. If poll response
frame 1 has bit 10 on (indicating outstanding status), the
system responds with a 'read status' command.
4-8
Reset (00000010) allows printing to be completed for
any line that was being printed when the ' reset'
command was received. The M PU responds as it would
for a power on reset that:
• Degates the cable driver and receiver (printer goes
offline).
• Turns off the Ready light.
• Runs power on diagnostics, as during power on
sequence (190).
• Sets default options (forms length 1 line, line length
132 characters).
• Clears the mode that was set.
• Gates the cable driver and receiver (printer goes
online).
• Presents the power on transition status response.
Set Mode (0001 0011) causes the printer to accept 1
mode control byte that specifies the number of times an
8- bit fill increment will be repeated between frames.
The fill increments are used to adjust the response
timing of stations attached to the controller. The' set
mode' command must be issued before any multiframe
response is made by the printer.
Write Control Data (00000101) is followed by a frame
that conditionally resets outstanding and exception
status.
Write Data (0001 1110), causes the printer to store all
the data words that follow the next activate write
command.
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