[Coco] Navigating around a 32 column screen.

[Allen Huffman]

> On Jan 27, 2023, at 10:48 AM, coco--- via Coco <coco at maltedmedia.com> wrote:
> 
> To All
> 
> Wanted to know if there is a way to reposition the text cursor to anywhere
> on a 32  column screen also is there a way to poke arbitrary text to a
> specific spot on the screen and is there anything in RS-DOS that is the
> equivalent of inkey in basic09 ?
> 
> I have an idea for a hex editor and to avoid it being one line at I time
> these capabilities would be required. Haven't done much Disk Basic
> programing lately.

Two approaches:

1) POKE to the screen memory (1024-1536). Some character POKE values will not match CHR$() PRINT values.

2) PRINT@ to a screen location (0-511). You cannot PRINT@ to the bottom right of the screen as it will make everything scroll, and anything you PRINT@ to the bottom line needs a semicolon at the end to avoid scrolling the entire line, as well.

INKEY$ works — directly or through a variable.

100 IF INKEY$=“” THEN 100

100 A$=INKEY$:IF A$=“” THEN 100
110 IF A$=“K” THEN…
120 IF A$=“L” THEN…

More advanced, is using INSTR() to locate a character in a string, and use that position for ON GOTO.

100 A$=INKEY$:IF A$=“” THEN 100
110 A=INSTR(A$,”ABCDEF”):ON A GOTO 200,300,400,500,600,700
…
200 ‘A
300 ‘B
400 ‘C
…etc…

You could also do ON GOSUB and then RETURN from the routines rather than having to GOTO back, if speed is important.