Acornsoft FORTH

Working with FORTH

TAPE - Select cassette for storage.
DISK - Select floppy for storage.
CREATE-SCREENS - Rewrite floppy to crate screen files for storage. (Nddds to be DFS formatted first)
3 LOAD - Load screen 3 (on tape it is the editor) and execute.
30 LIST - Load screen 30 (if not loaded) and print its contents.
SCR @ . - Prints recently listed screen number.
SAVE - Save current screen (lists and asks before saving).
SAVE-BUFFERS - Save all screens in memory to disk.
FLUSH - Zero all screens memory.
PROGRAM - Initializes empty screen (asks for number). Enters editor mode.
EDITOR - Enters editor vocabulary.
FORTH - Enters core vocabulary.
--> - Load next screen.

Screen commands:

P - Put text onto line.
D - Delete the line, moving up the lower lines to close the gap, but hold the deleted line at PAD.
E - Erase the line, leaving it blank. The contents of the line are not saved.
H - Hold the contents of the line at PAD. The line also remains in the screen.
I - Insert the text from PAD at the specified line. The lower lines are moved down to make room for the insertion and line 15 is lost.
R - Replace the contents of the line with the text from PAD.
S - Spread the text by inserting a blank line. Line 15 is lost.
T - Type the contents of the line and also copy it to PAD. The text remains in the screen.

Line editing (each command also lieves given text in PAD):

C - Insert the given text at the current cursor position.
F - Find the given text and position the cursor immediately after its first occurrence.
TILL - Delete all text, from the current cursor position to the end of the text given. This command will only act on text within a single line of the screen.
X - Find and delete the first occurrence of the given text.
N - Find the next occurrence of the text at PAD
B - Move the cursor back by the number of characters in the text at PAD.
DELETE - (count --) Delete count characters, backwards from the current cursor position.
M - (count --) Move the cursor by count characters, either forwards or backwards depending on the sign of count. The text itself is unchanged M is a simple way of displaying the current cursor position!

Word	Stack effect	Description
`.`	`( n -- )`	Dispaly signed number followed by one space
`U.`	`( u -- )`	Same as above but unsigned number
`D.`	`( d -- )`	Same as above but double signed number
`.R`	`( n n2 -- )`	Display signed number `n` in right side of filed of width `n2`
`D.R`	`( d n2 -- )`	Same as above but double signed number
`H.`	`( u -- )`	Display unsigned number in hexadecimal form
`DEC.`	`( n -- )`	Display signed number in decimal form
`." <text>"`	`( -- )`	Display text literal

Acornsoft Forth uses memory used by hi-res modes; only mode 4 and 5 are available.

Modes:

HEX
5 MODE
: CLS 7FFF 5800 DO FF I C! LOOP ;

In mode 4 this leave out space between lines of text, but if I switch to mode 5 and back to 4 it works fine. Also this is slow...

This is addressed in columns bytes 0-7, and then next column. So it is like character mode?

VDU can be used to clear the screen faster:

HEX
10 >VDU