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The method of tabbing to be used is specified by the
character sequence employed. The Horizontal Tab (HT)
character alone executes a Normal Tab operation: an
ESC HT initiates an Absolute Tab.
Since tabbing provides positioning only to normal print
positions, finer positioning requires the use of spacing in
Graphics mode.
3.6.2.4.1
Normal Horizontal Tab.
Tab stops can be set
or cleared, and tab commands executed, either locally or
remotely. Tab stops can be set at any print position up to
position 160. Once tab stops are set, execution of a
Horizontal Tab (HT) can be initiated from either the
keyboard or the communications link, and causes the
carriage to seek the next tab stop set to its right. Should an
HT be executed with no tab stop having been set to the
right of the present horizontal position, the carriage will
move to the rightmost print position.
Tab stops can be set by first position ing the carriage to
the desired print position and then executing an ESC 1
sequence. Keeping in mind that the tab stops can be set at
only the first 160 print positions, the formula for determin-
ing a tab position is as follows:
horizontal tab position (1-160) =(horizontal Position)+l
HMI
Subsequent TAB operations automatically move the
carriage to the next sequential tab stop to the right.
Individual tab stops are cleared by first tabbing to the stop
to be cleared and then executing an ESC 8 sequence; all tab
stops are cleared at one time by execution of an ESC 2
sequence. If Graphics mode is used, operation can be
slightly different. See 3.6.2.5.
3.6.2.4.2
Absolute Horizontal Tab.
Using Absolute Tab,
the carriage can be positioned directly to any of the first
126 print positions without the need for prior setting of tab
stops. This is accomplished by preceding the Horizontal
Tab command (HT) with an ESC character, and following it
with the ASCII character whose decimal value indicates the
print position desired (see Table 3-2).
Note that this method of tabbing also makes possible
tabbing to the left.
For example, with the carriage
positioned at print position 100, an ESC HT 1 sequence
will move the carriage directly to print position 49, the
decimal value of the ASCII code for digit 1. The leftmost
print position is considered location 1. Any ASCII char-
acter other than NU L and DE L can be used, making
possible direct tabbing to any of the first 126 print
positions. The horizontal position at the completion of an
Absolute Tab operation is computed as follows:
horizontal position
=
(ASCII character -
1)
x HM I
3-6
The 3-character tab sequence can be issued from the
keyboard or from the communications link. Note that in 10
or 12 characters-per-inch, the final position indicated on
the combination scale will be one less than the actual print
position, since the scale numbering starts at
a
instead of 1.
Absolute Tab is unchanged in Graphics mode.
3.6.2.5
GRAPHICS (ESC 3, ESC 4)
To take advantage of the HyType's graphics capability,
the HyTerm can be placed into Graphics mode by reception
of an ESC 3 sequence. The HyTerm remains in Graphics
until a Carriage Return or an ESC 4 sequence is executed.
While in Graphics, carriage movement is completely
divorced from printing: i.e., printing a character does not
automatically move the carriage. The carriage can be moved
only by executing a tab, space, carriage return, or back-
space operation.
In Graphics mode, the space and backspace commands
move the carriage only 1/60 inch instead of the selected
horizontal index amount. Absolute Horizontal Tabs operate
the same in Graphics as in Normal mode. However, Normal
Horizontal Tabs always move the carriage some mUltiple of
the HMI, so if the carriage is not resting precisely on a
normal print position when the tab is executed, it will also
be off at the completion of the tab. The same is true of tabs
performed after leaving Graphics via the ESC 4 sequence.
To insure proper tab operation in Graphics and after leaving
Graphics, make sure the carriage is positioned at a normal
print position before the tab is executed or before the
ESC 4 is performed. I n all cases, a subsequent carriage
return will resynchronize tab stops with print position.
The tab commands operate the same as they do in
Normal mode. In Graphics mode, however, the space and
backspace commands move the carriage only 1/60 inch
instead of the selected horizontal index amount.
Paper movement commands can be heavily util ized in
Graphics. Vertical Tab (VT) and Form Feed (FF) opera-
tions are unchanged in Graphics, but Line Feed (LF) and
Negative Line Feed (ESC LF) cause only 1/48 inch of paper
movement, instead of the full line (VMI) movement they
effect in Normal mode.
3.6.2.6
FORWARD/BACKWARD PRINT (ESC 5/ESC 6)
To enter Backward Print mode an ESC 6 sequence is
used. An ESC 5 sequence or a carriage return will reestab-
ish Forward Print mode.
During Forward Print each character printed also causes
incremental carriage movement to the right (except during
Graphics). During Backward Print this motion is reversed,
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