Chapter 2.
P E R A C T O R
Editor (EDITOR) - is encased in a
ROM program that promotes human-computer interaction: data
entry, their modifications and adjustments. All that
we type on the keyboard, usually appears at the bottom of the
screen. Any text in this area can be modified or
edit. Keys and
(Left and right arrows in the ZX-SPECTRUM +)
can move the cursor along the current line without erasing the
information. To erase characters, key
( In the ZX-SPECTRUM +). Erased character
located immediately before the cursor, and the BASIC keywords
are treated as individual characters.
During the recruitment program or operational directives
editor in many cases (After entering a keyword, ":", THEN and
etc.) itself changes the input mode (between K,
L, C), protecting the user from accidental
errors. But if such a mistake should be done
specifically, it is possible to "cheat"
inserting, for example: "for the regime K, and then removing
it. Such deception, Of course, not preclude the subsequent
troubles with the incorrect line in program.
End of edit, input, command line or the next program line
indicated by the key <ENTER>. PC lightning checks the syntax
(ie, correct use of language elements
BASIC). In case of necessity, in a strange place to him you see
a flashing sign question. It may appear much
more than a mistake, for example, in the absence of a closing
parentheses. In a complex SPECTRUM expression is unable to
determine the place where it was necessary to insert and will
signal an error only at the end of the expression.
But the perception of the line computer does not guarantee
the correctness of its logic, nor agreement with the wishes of
the author.
There is no way to force the computer to
remembering wrong (in terms of syntax
BASIC, not the logic of the program) a sequence of commands.
Incidentally, this means that without joining INTERFACE ZX-1
can not even prepare a control program for the exchange with
the memory type MICRODRIVE, because you can not even enter
enough for this specific commands.
If the corrected position available
control characters, moves the cursor
sometimes behaves strange and unusual (disappears, retreating).
It is not necessary because of this upset. In the process of
removing such characters may appear as question marks, which
should be removed separately - These control characters are
normally occupy 2 bytes of memory and SPECTRUM, the forced
illuminate the sign code less than 32, brings in its place a
question mark, if can not interpret it differently.
To correct already entered into the memory
line program, you have to first
copy at the bottom of the screen. With this
to move the current row
(>) Up and down keys and
(To ZX-SPECTRUM + - and up arrows
down). At longer programs faster using instruction LIST n. Can
enter the number of slightly less than the number
desired line, if you are confident that
program is no line with that number, you do not accidentally
overwrite the row. After clicking <ENTER> pointer will be set
on the first line number greater than specified. Or at the
latest, if not specified in the program. Pointer ">" after such
an enterprise, may be temporarily invisible, but after clicking
( <EDIT> In the ZX-SPECTRUM +) the desired line will be
copied into the working field of the editor.
Pressing one <ENTER>, with empty bottom of the screen leads
to the emission fragment program, which includes current
string (pointed to ">"). Once we can introduce the operator of
any length. Initially, the lower portion of the screen will be
automatically extended, but gradually the computer will react
more slowly, Signaling a growing dissatisfaction
human actions. After storing 22
rows protest computer will be much sharper. He no longer
highlight the following characters, the keyboard and every
keystroke respond unpleasant nag. But despite this, he continue
to accept and remember all that you earn. Its resistance can be
mitigated, modifying the relevant system variables. Key
(<EDIT>) also allows a one-time removal of the entire bottom of
the screen.
