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DIDS-402-2AM13
4-11 MESSAGE FORMAT, ENQUIRY-RESPONSE
The mes sage formats for the enquiry- response conversational mode are
illustrated in figure s 4-5 and 4-6 and described in the accompanying text.
4-11. 1 Enquiry Format
The display terminal enquiry to the CPU is in the format shown in
STX
DA
TEXT / COMMAND
ETX
OIOS 68-504
Figure 4-5.
Enquiry Message Format
a.
STX - This character has an ASCII control code of 0000010 and is
always the first character of any message.
b.
DA - This character can assume anyone of 64 separate ASCII
codes, depending upon the address assigned to the particular Display
Te rminal.
.
c.
TEXT - rhese characters consist of displayed characters shown on
the display terminal screen.
From 1 to 1039 text characters are
transmitted, depending upon the length of the message.
d.
COMMAND - These characters are produced by depressing the
CONTROL key and anyone of several alphabet keys.
For example,
depressing the CONTROL and Q produces the DCl command charac-
ter.
Depending upon the CPU program, DC1 can be used at the CPU
to accomplish a control action.
e.
ETX - This character has an ASCII control code of 0000011 and is
the last character transmitted in any message.
The ETX character
is usually inserted into the display terminal delay line when the END
key is depressed.
4-11.2 Re sponse Format
The CPU re sponse to a display terminal enquiry is in the form.at shown
in figure 4-6.
STX
DA
TEXT/COMMAND
ETX
OIDS 68-505
-Figure 4-6.
Response Message Format
.a.
STX - Described in paragraph
4-11.1~.
4-12
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