Book - Secrets ZX-Spectrum: Editor.

<b>Book</b> - Secrets ZX-Spectrum: Editor.

   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.