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From: howellg@idec.stc.co.uk (Gareth Howell)
Newsgroups: comp.lang.forth
Subject: Re: TIL design topics
Message-ID: <754@argon.idec.stc.co.uk>
Date: Thu, 20-Nov-86 04:59:15 EST
Article-I.D.: argon.754
Posted: Thu Nov 20 04:59:15 1986
Date-Received: Fri, 21-Nov-86 21:47:52 EST
References: <1001@usl.UUCP>
Reply-To: howellg@idec.stc.co.uk (Gareth Howell)
Organization: STC Network Systems, Stevenage, UK
Lines: 28
Keywords: Roll Your Own Language

In article <1001@usl.UUCP> elg@usl.UUCP (Eric Lee Green) writes:
>
>I am currently designing a small threaded language in which to program
>my fairly new Commodore 128. I don't particularly like FORTH, it is
>excruciatingly slow on a 6502, and the command names are just aweful
>(comeon now, "!"? "."? ":"? Gimme a break!). But I do like the general
>FORTH idea. So, I'm looking for comments on these implementation
>decisions:
>
>subroutine-threaded: Instead of threads being two-byte machine
>addresses, have a jsr <address> machine instruction instead. Immediate
>advantage is speed (NEXT is very slow on a 6502), at a cost of making
>the program 3/2 larger. The largest FORTH I've ever seen for the 6502
>was only 25K. My C-128 has 128K of RAM. Space is hardly a problem.
>
Have you considered swapping your 6502 for a Western Digital 65802
processor.  This is a pin for pin replacement that has an expanded
register and instruction set; including instructions that speed up
words like NEXT.  Have a look at "Implementing FORTH on a New
Processor: FORTH for the 65816 and 65802" by John Bowling of Starlight
FORTH Systems.  It was presented at the 1984 Rochester FORTH
conference.

I don't have any personal experience of this mod. 'though it is on my
hit list for my BBC micro, but the author claims a doubling in
execution speed and a reduction of nearly a third in code space
occupancy without ny other hardware mods.
	gareth