Quick Forth Question
John R. Hogerhuis
jhoger at pobox.com
Tue Jan 24 03:04:30 CST 2006
On Tue, 2006-01-24 at 02:10 -0500, Roger Merchberger wrote:
> Dudez & Dudettez:
> I'm trying to get some SnapForth ROMs running for the Panasonic HHC 'puter
> - and I'm having a bit'o'difficulty, mainly as I know... ummm... "squat"
> about Forth. ;^>
> I've gotten the ROMs to be able to start SnapForth, ask for a filename,
> create the filename & filespace (about 1K of RAM goes "buh-bye" for every
> filename I make... ;-) but no matter what I type, all I get is "Can't Find
> xxxxx" where xxxxx seems to be any durned thing I type.
> It can't seem to make new words, and every simple "Hello World" type
> proggie I've found on the net makes *no* sense to the 'puter.
Usually ." Hello, world." words on all forths.
Keep in mind you do need the space between ." and the first letter of
the string, since ." is a word (a "parsing" word since it reads ahead in
the stream till the ending ")
> It looks like it has a max. of 4-character words... duh, waitaminit...
> lemme check the ROMs again... *maybe* 5-character words, as it looks like
> the last character of the word is OR'ed with $80... It looks like it's got
> quite a few words, looking at the ROMs in ASCII - I found VARIA, CONST,
> STRIN, CVECT, JUMP....
The way old Forths worked was that they saved space by matching the
first 3 characters of the name and the length. So VARIABLE != VARIANT
since the lengths are different. Maybe yours does have 5 character
> I could provide a clip of the ROM word table if it would help...
Might help. Sometimes you can also type WORDS at the command prompt and
see all the words.
> I've tried:
> 100 LLL !
> [[ To try to store the variable 100 in LLL ]]
You mean try to store the value 100 in the variable LLL.
Well, first you need to create the variable:
Then you store a value in it:
100 LLL !
> 100 VAR DORK
> 100 VARI DORK
> 100 VARIA DORK
> 100 VARIABLE DORK
Type the whole word.
Are you trying to make a variable or a constant?
100 DORK !
DORK @ .
100 CONSTANT DORK
Newer Forths have a word called VALUE which is close to the semantics
you made up for VARIABLE.
Also, you can just use CREATE as so:
> [[ To try to store the variable 100 in DORK ]]
> 100 CONS BURP
> 100 CONST BURP
> [[ To try to make BURP a constant of 100 ]]
the word is CONSTANT
> I've also tried:
This word prints out the contents of the stack. If you put something on
there first, it should print something.
1 2 3 4 5 .S
Don't do this unless you have something on the stack to drop. Actually,
try it it should give you an error if there's nothing on the stack.
> ." Hello World"
That should work in most Forths.
> and other things I'd seen in various webpages thanks to Google.
> Anyone got any other idears for me?
Try to do some arithmetic ala
100 2 * .
Next step is a simple word like SQUARE
: SQUARE DUP * ;
5 SQUARE .
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