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INPUTTING DATA
CHARACTER MODE. When inputting data in
character mode, the overstrikes may be done in any order
on the current line. You may type several characters, then
backspace as far as necessary to begin generating the
overstrike characters, skipping over characters when
necessary by using the space bar. (The APL System keeps
track of your current cursor position by monitoring the
number of backspaces and forward spaces.) When the line
is complete, press RETURN to indicate to the system that
the line is terminated.
Since blanks do not overwrite existing APL characters on
the display and all attempts to overwrite will result in
overstriking, the method for input correction is to use the
Line Feed (LF) character. You backspace to the character
to be edited, then send an LF which effectively erases
(according to the APL System) all characters to the right
of the point where the LF occurred. The new characters to
be typed are appended to the current characters at the
point where the LF occurred to complete the meaning of
the input data or command.
When using the 2641 with the HP APL"'.3000, an
additional means of input editing is available. The
CNTL-Y character (Em) can be used for input correction.
When you input CNTL-Y, the HP APL"'. 3000 will send an
escape sequence to the terminal to clear the line from the
current cursor position. It is an easy matter to append the
corrected data to the line. Also, the HP APL"'. 3000
recognizes CNTL-Y as an attention command code which
is useful to break infinite loops when running a program.
BLOCK MODE. When operating in Block Mode, the
ENTER key is used to input data (as in ASCII Mode) after
~he
data on the screen has been edited (corrections made
where necessary and overstrikes generated). Overstrikes
are decomposed to their component characters with a
backspace character between them. For example, the
~
character would be sent as [, Bs, o. Any number of
Display Memory Functions
overstrikes (up to 80 characters, maximum) may be sent
on an input line.
DISPLAY ENHANCEMENTS
The 2641A Terminal has the display enhancement feature
as standard equipment. Also, the enhancement charac-
ters can be entered in ASCII Mode or APL Mode. When
in APL Mode, either the SHIFT key or the CAPS LOCK
key must be down when pressing the enhancement
character key (A through
0)
except the
@
key.
ALTERNATE CHARACTER SETS
The 2641A terminal has three character sets as standard
equipment:
•
64-character Roman base set (Set
@)
•
128-character APL set (Set A)
•
64-character APL Overstrike set (Set B)
A 64-character lowercase Roman set can be optionally
added. Also, either a Math, Line Drawing, Large
Character, or User-Defined character set can be optionally
added as Set C.
When the terminal is in ASCII Mode, Set @ is the base
set. In APL Mode, Set A is the base set. Alternates may be
defined by the user as described earlier in this section.
For block transfers to the CPU in APL Mode initiated by
the READ key or ENTER key, whether from the display or
cartridge tapes, the default character set to be transmitted
will be the APL set (Set A). No shift-in (SI,17 octal) or
shift-out (SO,16 octal) characters will be transmitted
when APL-only data is transmitted. The overstrike
characters will be decoded and transmitted as APL
characters separated by a backspace character.
2-15/2-16
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