Path: utzoo!attcan!uunet!husc6!bloom-beacon!apple!rutgers!att!alberta!calgary!cpsc!demarco
From: demarco@cpsc.ucalgary.ca (Vince Demarco)
Newsgroups: comp.sys.apple
Subject: Re: Mad Apple Forth
Summary: forth
Keywords: Did I read the advertisement correctly?
Message-ID: <883@cs-spool.calgary.UUCP>
Date: 13 Mar 89 00:23:48 GMT
References: <1249@tellab5.tellabs.CHI.IL.US>
Sender: news@calgary.UUCP
Lines: 42

In article <1249@tellab5.tellabs.CHI.IL.US>, toth@tellab5.tellabs.CHI.IL.US (Joseph G. Toth Jr.) writes:
> Boy, was I excited...
> This thing is not a compiler.  It is an interpreter...
> Nor could I read the secondary disk. NOT A ProDOS DISK.
> 
> I mean, what is going on here.

> whatever that is.
> Makes it awfully hard to use with a Hard Disk, doesn't it,
> always having to insert the thing in a 5 1/4 inch drive in slot 6 drive 1
> every time you want to use the prrograms, or even if you boot from that drive
> when you don't have a hard disk (probably worse). I sure seems inflexible,
> but then the forth language doesn't allow for drive or file selections, it
> reads data in something called screens (something like a block of data,
> kind of like a file (but not really).  Sound confusing?? It is to me, and
> I've programmed in most languages around (a computer engineer, graduated
> from UMR in 1975, and been using computers ever since).

Well most "real" forths are "semi-compilers", their base functions are in pure
machine language and the system compiles your user functions made purely out
of jsr and jmp to those base functions...   "real" forths ARE compilers in the
sense that they generate romable machine code (albeit rather large), and they
are ALSO interpreters in that the code they generate are available as you type
(if you do it that way, if you use an editor to write code, then the process is
the same as a standard compiler)
Forth "screens" are a form of virtual memory... In a version of forth83 I have,
unlimited "screens" per file are supported.. screens may contain program code
or data..  the words UPDATE and FLUSH and CLOSE (somewhat analagous to unix
SYNC) allow you to manipulate the VM and swap to disk... in fact many IBM and
other forths are multiuser/multitasking systems!!! (my apple f83 is
multitasking (albeit slowly)!!).. I believe "screens" are rather antiquated..
they were used back when one had a whole disk/tape to himself and the whole of
the mass storage device could be used for his "screens".. (My f83 supports the
use of screens within FILES).. you can think of screens as "pages" used in a
more advanced VM system...
I guess if you want, I could upload that forth (also PD, ProDOS based) for
everyone to look at... 

Chris.. (posting from a friend's acct)

Disclaimer-> I know absolutely nothing about this... :-)
Replies-> CYLau@UNCAMULT.BITNET