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Generally speaking, most users will want
to use the Spectrum editor to type and edit the source, but a full Forth Line
editor is included for compatibity with existing text. The maximum length of any
line is 64 characthers. Any characters after this will be ignored.
The Line Editor
Included in this version of White
Lightning is a Line editor to enable you to create source or text files. To
facilitate text editing, the text is organised into blocks of 512 bytes, divided
into 8 lines of 64 characters. Once the text has been edited, it may be compiled
into the Forth dictionary and the text, if required, can be saved to tape. The
text editor is stored in memory in the pages at C000 to F000, therefore you can
edito into screen 1 to 23. If the background facility is utilised, text is
stored from CC00 onwards in screen 6 to 23, and screen 0 to 5 cannot be used.
Here is a list of the editor commands and their descriptions.
H
This will Hold
the text pointed by the top number on the stack of the current screen in a
temporary area known as
PAD
e.g.
4 H
will hold line 4 of the current screen
in PAD.
S
Fill (Spread)
the line at the top of the stack with blanks, and shift down all subsequent
lines by 1, with the last line being lost.
e.g.
6 S
will fill line 6 with blanks and move
all others lines down by one pushing the last line off the screen.
D
Delete the line number hold on the
stack. All other lines are moved up by 1. The line is held in PAD
in case it is still needed. Line 7 cannot be deleted.
E
Erase the line number at
the top of the stack by filling it with spaces.
RE
REplace the line number at
the top of the stack with the line currently held in
PAD.
INS
INSert the text from the PAD
to the line
number held on the stack. The original and subsequents lines are moved down by
one with the last line being lost.
P
Insert (Put)
the following text to the line
number held on the stack. The original content of the line is lost.
EDIT
Works just like normal Sinclair line
editor. Also, it does an automatic LIST and an automatic
FLUSH. This is far and
away the best way to edit and the above are included only for compatibility with
existing Forth's.
CLEAR
CLEARs the screen number held on the
stack and make it the current screen.
WHERE
If an error occurs during the LOADing of
Forth’s text screen, then keying in WHERE
will result in the screen number and offending line being displayed. You can use
the other editing commands to edit the screen, or you may move to another screen
by either LISTing or CLEARing
it.
e.g.
15 LIST
will now make screen 15 the current
screen and will list the contents. In order to compile this screen into. the
dictionary, it is necessary to use the word LOAD.
LOAD
This will start loading at the screen
number held on top of the stack and will stop at the end of the screen. If you
wish to continue and LOAD the next
screen, the current screen must end with -->.
This means “continue loading and interpreting”. If you wish to stop the LOADing
anywhere in a screen then use ;S. This
means “stop loading and interpreting”.
At the end of every editing session and
before saving your text, it is necessary to FLUSH
the memory buffers into the text area. To do this, just key in
FLUSH <CR>
Note that the EDIT
command does automatic FLUSH. You can
save your text to tape using the Spectrum SAVE command. You must first enter in
BASIC typing
PROG <CR>
Now for an example of how to edit a text
file, the first step is to either LIST or
CLEAR the screen about to be worked on
9 LIST
followed by the text below
0 P THIS IS HOW TO PUT
<CR>
Then type
1 P TEXT ON LINE 1 <CR>
and so on, until you have entered:
THIS IS HOW TO PUT
TEXT ON LINE 1
LINE 2
AND LINE 3 OF THIS SCREEN
Now:
9 LIST <CR>
will produce
SCR# 9
0 THIS IS HOW TO PUT
1 TEXT ON LINE 1
2 LINE 2
3 AND LINE 3 OF THIS SCREEN
4
5
6
7
To change line 2 type
2 EDIT <CR>
and then change it in the normal way to
insert ‘TEXT ON’ before ‘LINE
2’. Now type
9 LIST <CR>
to see the result. The editor ignores
character after the 64th character of the line being edited.
If you have a Sinclair Printer
connected, then it is probably worth defining a word to list screen to the
printer:
: SLIST PRT-ON 1 = SWAP
<CR>
DO 1 LIST CR LOOP PRT-OFF ; <CR>
To use the above word, type the first
screen number, last screen number, SLIST.
e.g.
6 9 SLIST <CR>
will list screen 6 to 9 to the printer.
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