Subject: Re: FORTH

From: Charles Esson <[email-masked]>
Date: Fri, 16 Jan 1998 09:14:44 -0500

Ka'Plaagh wrote:

> I don't think that it's strange, we used forth on the EBSA285.  I presume that
> you're using the work that Neal Crook did (he also did the EBSA110 forth stuff)
>
> Dave
>
>

I didn't even know about it, and I wish I had. I have just spent 4 months getting
wimpFORTH into shape for a port from riskOS to a stand alone version. It is now
very neat, with no magic numbers, producing separate dictionary and memory area
code ( so the dictionary can be MMU protected) and was ready for multitasking on
the SA110.

The SA1100 with it's task register changed that. While the version for the SA110
used registers for the base address of the user area ( a task specific memory
block) and the global memory area. I think the SA1100 makes it possible to move
this problem to the MMU tables, without having to do anything more than writing a
new value to the task register on a task switch.

I must say that task switch register is the simplest and neatest thing I have seen
in years. It makes it possible to use a MMU to protect the applications from
themselves and each other with very minimal overhead. A real plus for real time
control. I take my hat off to the hardware gods at digital.

As I am waiting impatiently for the delivery of brutus, the next job is the
downloading of Neal's stuff and having a look.

Regards

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From: "Ka'Plaagh" <[email-masked]>
Date: Fri, 16 Jan 1998 14:38:19 +0000

OK, I'll keep a watching brief.  Right now we're righting the bootloader/flash
management code so that angel on brutus can boot images out of the second
banks of flash.  These banks are programmable, the base pair are not.   I would
suggest that you hack/write forth to take advantage of this.  I can update your
angel images etc when we've done this work and I am interested in your forth
work.  I'm also interested in Linux on the 1100...

Dave

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David A Rusling				Consulting Engineer
European Semiconductor Applications	Digital Equipment Co Ltd.,
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