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Graphics
Programming Considerations
When
SCALED
or
SCL 401 4
mode is selected via the Terminal Configuration menu, applying
power to the terminal or executing a hard reset turns on the graphics cursor and positions it in
the upper left-hand corner of the screen display, emulating the 4014 function. When 4014 mode
is selected programmatically, the state of the cursor and pen is not changed.
8-BIT MODE. Characters sent to the terminal in 4014 mode have their parity bit cleared
automatically. Thus the ROMAN extension character set is not accessible in 8-Bit and
Tektronix-modes. 7-bit mute processing retains its normal function.
GRAPHICS STATUS
You can request graphics status information in addition to normal terminal status data. All
graphics status requests are initiated by sending an
Ec
*
5
followed by a single parameter
(1
through
1 2)
and terminated by a .The single parameter selects the desired status block. If an
invalid parameter is used, the terminal responds with its ID (see Device ID Request, parame-
ter=l).
Graphics Status request:
Ec
*
5
<parameter> "
where
Ec
*
5
is the graphics status escape sequence.
<parameter>
is
1-12
and selects one of twelve blocks of graphics status data.
The graphics status blocks that can be requested are listed in Table D-15 together with the
format of their terminal's response. Detailed descriptions of each status request are found in
the following paragraphs.
The terminal responds with one or more bytes of status information followed by a block
terminator. All status information is 'in ASCII format, with commas as separators. Coordinates
are returned in a fixed format consisting of a sign and five digits. Leading zeros are used as
required to provide a fixed number ofdigits (ie +00100, -01234). This allows you to use simple
input statements without needing to mask or shift bits.
If DC1 handshake protocol is enabled (ie,
ttNO"
is entered in the
ttInhHndShk(G)"
and
tt I
nhDC2 (H)"
fields of the Terminal Configuration menu), the status block is not actually sent
until receipt of a DC1 character. If the DC1 character is used, only one graphics status request
can be enabled while the terminal is waiting for a DC1. When the DC1 is received, the last
graphics status block requested is sent to the terminal.
While the terminal is waiting for the DC1, the Device Status Pending bit is set.
D-53
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