Arthur for A500 Second Processor

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Boydie
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Arthur for A500 Second Processor

Postby Boydie » Sun Jul 09, 2017 12:51 pm

Another set of disks rescued from Acorn following Black Thursday.
They appear to be a development of Arthur (Release 3) for a BBC with A500 Second Processor, so are probably of use to a very limited group! I don't know if they'll work on a BBC/A500 Tube podule combination, but I'm guessing probably not.

They consist of:

Rel 3 Discs 1-3, apparently intended to install Arthur to the BBC's Winchester
Supplement 1
Supplement 1a - WIMP/Font
Arthur C Compiler
Attachments
ArthurRel3.zip
(1.29 MiB) Downloaded 38 times

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danielj
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Re: Arthur for A500 Second Processor

Postby danielj » Sun Jul 09, 2017 1:12 pm

Wow. Flibble will be very interested in this!

d.

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flibble
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Re: Arthur for A500 Second Processor

Postby flibble » Sun Jul 09, 2017 2:49 pm

Blimey, that's a good find. Earliest Arthur/RISC OS yet! (I think)

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BigEd
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Re: Arthur for A500 Second Processor

Postby BigEd » Mon Jul 10, 2017 8:48 am

Is this the sort of thing we could get running with PiTubeDirect or with the Matchbox copro? They both offer ARM2 processors.

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Re: Arthur for A500 Second Processor

Postby RobC » Mon Jul 10, 2017 9:05 am

BigEd wrote:Is this the sort of thing we could get running with PiTubeDirect or with the Matchbox copro? They both offer ARM2 processors.

The A500 had sockets for VIDC, MEMC and IOC (as well as the ARM) and so I think it's likely that much of this stuff will be using them.

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BigEd
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Re: Arthur for A500 Second Processor

Postby BigEd » Mon Jul 10, 2017 9:14 am

Ah.. so the host Beeb would be used for keyboard and filesystem? Might it send output to the Beeb too? In which case the on-board video would be the super-special GUI framebuffer but good old standard input and output would be the host?

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Re: Arthur for A500 Second Processor

Postby RobC » Mon Jul 10, 2017 9:32 am

BigEd wrote: Might it send output to the Beeb too?

I guess that's possible but the development of the A500 on Chris's Acorns indicates that they got video was up and running first (and the A500 had it's own RGB socket) so they may not have needed vdu output on the Beeb side for very long.

http://chrisacorns.computinghistory.org.uk/Computers/A500.html

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BigEd
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Re: Arthur for A500 Second Processor

Postby BigEd » Mon Jul 10, 2017 9:45 am

I suppose the question is how the OS calls are made and how they are directed. And whether they could be shimmed on a Pi to call over the Tube. I'm sure there's no question of getting a GUI running on the Beeb side, but maybe a CLI?

From your link:
Originally these machines were hooked up to BBC micros via an umbilical into the tube port and all the I/O was done by the Beeb. Over time we gradually got the various sub-systems alive, and moved them over to the A500 native. First the video and graphics, then the keyboard, then the file systems and so on. This machine was on my desk when for the very first time ever we removed the umbilical, and rebooted it - and watched it come up to the basic prompt on its own. Arthur was born!

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Re: Arthur for A500 Second Processor

Postby Boydie » Mon Jul 10, 2017 10:55 am

Bear in mind that the A500 and A500 Second Processor (http://chrisacorns.computinghistory.org ... rocAL.html) are very different beasts. A friend at ARM who had both reckoned that the 2P preceded the full A500, so by the time the A500 was available most of the necessary hardware may well have been supported. Or maybe not, given that Acorn developed the Tube podule.

Looking at the A500 2P, I'm guessing that SK2 may be an RGB socket. SK4 looks very much like the keyboard connector on an A500. Oddly, it doesn't appear to have a Tube connector (or ULA) or board, but does have a podule connector. Maybe the Tube podule plugged into that...

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BigEd
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Re: Arthur for A500 Second Processor

Postby BigEd » Mon Jul 10, 2017 10:59 am

SK5 must be the Tube connector, with the 40-pin socket for the ULA next to it?

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BigEd
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Re: Arthur for A500 Second Processor

Postby BigEd » Mon Jul 10, 2017 11:08 am

Some not-entirely-unrelated boards I've snapped previously:
Image
Image
Image
Image
But here's one like the one in question:
Image
Image
Image
Image

Boydie
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Re: Arthur for A500 Second Processor

Postby Boydie » Mon Jul 10, 2017 11:10 am

That's my guess, but whilst the Tube ULA could have been removed, it doesn't look as though SK5 was ever fitted. There must have been some other way of hooking it to the Tube, and the podule method does make some sense since the on-board Tube support code for both 2P and full A500 would then be the same. There was no code on the podule, at least no ROM that I can see!

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BigEd
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Re: Arthur for A500 Second Processor

Postby BigEd » Mon Jul 10, 2017 11:18 am

Ah, yes, unpopulated connector is a clue!

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jgharston
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Re: Arthur for A500 Second Processor

Postby jgharston » Mon Jul 10, 2017 4:45 pm

Somewhere I've read a history of the development of Arthur on the A500 which included something like:

"we tenatively unplugged the Tube connector, pressed the RESET button, and it successfully booted to the Arthur supervisor prompt running on its own hardware resources"

Edit: A ha:
From your link:
Originally these machines were hooked up to BBC micros via an umbilical into the tube port and all the I/O was done by the Beeb. Over time we gradually got the various sub-systems alive, and moved them over to the A500 native. First the video and graphics, then the keyboard, then the file systems and so on. This machine was on my desk when for the very first time ever we removed the umbilical, and rebooted it - and watched it come up to the basic prompt on its own. Arthur was born!
[/quote]

BigEd wrote:I suppose the question is how the OS calls are made and how they are directed. And whether they could be shimmed on a Pi to call over the Tube.
They were made via standard Tube I/O calls through a module called 'HostFS'. As the above quote shows, various functionality in HostFS was disabled as they got more and more native stuff working.

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.25
(C) Copyright J.G.Harston 1989,2005-2015
>_

Boydie
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Re: Arthur for A500 Second Processor

Postby Boydie » Fri Jul 14, 2017 8:59 am

Forgot to mention.
The BASIC (AB) works on the ARM Evaluation System and is rather special.

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BigEd
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Re: Arthur for A500 Second Processor

Postby BigEd » Fri Jul 14, 2017 9:36 am

AB is about the only thing I know of that we can run on the ARM2 flavours of PiTubeDirect and the Matchbox.
https://github.com/hoglet67/PiTubeDirec ... -arm2-core

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DutchAcorn
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Re: Arthur for A500 Second Processor

Postby DutchAcorn » Fri Jul 14, 2017 10:47 am

What about this Arthur C-compiler? Does that work on the ARM Eval system?
Paul

RobC
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Re: Arthur for A500 Second Processor

Postby RobC » Wed Oct 04, 2017 10:55 am

BigEd wrote:AB is about the only thing I know of that we can run on the ARM2 flavours of PiTubeDirect and the Matchbox.https://github.com/hoglet67/PiTubeDirec ... -arm2-core

DutchAcorn wrote:What about this Arthur C-compiler? Does that work on the ARM Eval system?

The C compiler on the ArthurC.adf image works on my Matchbox copro in ARM2 mode. It's version 1.39 of the Norcroft compiler - there's the even earlier version 1.31 on disk 1 but that doesn't have the libraries.

The syntax is:

cc helloW (with C source file helloW in directory 'c', object output goes to 'o' directory)
link -image helloW -adfs o.helloW -Library :$.arm.clib.ansilib

I also have version 2 of the Norcroft compier and that also works on the Matchbox and Pi copros. However, rather unfortunately, I'm not allowed to release it.


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