Second Processor Elite - How did it work?

reminisce about bbc micro & electron games like chuckie egg, repton, elite & exile

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PitfallJones
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Second Processor Elite - How did it work?

Postby PitfallJones » Thu Aug 18, 2016 8:45 am

I was wondering how to write a co-processor game.
What did Elite actually do on the second processor?
I'm assuming the screen memory and thus line drawing was still done on the BBC side?
Is there a disassembly of Elite CoPro out there?
Where there any other CoPro games?
PJ

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Re: Second Processor Elite - How did it work?

Postby richardtoohey » Thu Aug 18, 2016 8:56 am

Been discussed before, but I can't remember the answers! :D

viewtopic.php?f=2&t=8325
viewtopic.php?f=1&t=8877

Scroll about half-way down the first one - where I ask the same question, and keep going until Rich chimes in (a man who knows what he is talking about!)

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oss003
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Re: Second Processor Elite - How did it work?

Postby oss003 » Thu Aug 18, 2016 9:06 am

Ian Bell published the sources of Elite.
I used the Electron sources for converting Elite to the Atom.
IIRC including the 2nd processor version and Elite-A.

http://www.iancgbell.clara.net/elite/bbc/

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PitfallJones
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Re: Second Processor Elite - How did it work?

Postby PitfallJones » Fri Aug 19, 2016 9:31 am

Thanks for all those links - that's nice of Mr.Bell to post all the source!

So the Copro runs the game and sends line draw commands to the original BBC to process therefore there is enough ram freed up on the BBC to change the mode from Mode5 to Mode1!

It's a shame Elite was is the only game that uses the CoPro I can see that would enable many games to go 'full color'.

I had one myself but used it mostly to run rom images from ram (like View).

PJ

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Re: Second Processor Elite - How did it work?

Postby tricky » Fri Aug 19, 2016 12:18 pm

I was planning to do a similar thing to elite to emulate the hardware of more games (see Circus, RipCord and Sprint), including games that could then be run on the copro with the display on the beeb allowing bigger games with more display work as well as games not running an a 6502 - but that is just one more WiP.

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Re: Second Processor Elite - How did it work?

Postby geraldholdsworth » Fri Aug 19, 2016 1:06 pm

PitfallJones wrote:It's a shame Elite was is the only game that uses the CoPro I can see that would enable many games to go 'full color'.


Wasn't there a Co-pro version of Exile?
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Re: Second Processor Elite - How did it work?

Postby CMcDougall » Fri Aug 19, 2016 4:47 pm

^ just a SWR version that does nothing apart from more sounds /speech at start.
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Re: Second Processor Elite - How did it work?

Postby billcarr2005 » Fri Aug 19, 2016 7:03 pm

CMcDougall wrote:^ just a SWR version that does nothing apart from more sounds /speech at start.


+ it has a bigger display area to the top and bottom of the screen rather than seeming "windowed" :)

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Re: Second Processor Elite - How did it work?

Postby trixster » Fri Aug 19, 2016 10:42 pm

Correct. The Swram version of exile has a much bigger display than the standard version. It makes a big difference in my opinion.
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Re: Second Processor Elite - How did it work?

Postby tom_seddon » Sat Aug 20, 2016 12:19 am

I wrote an article about programming for the Tube: http://ffe3.com/tom/tube.html

This is the 2nd draft (same goes for the rest of the site). The technical info is sound enough, but I'm not 100% happy about the writing... but it might prove interesting anyway.

(Also - needs the demo programs putting on an SSD. I use John Kortink's 65Link, so it's a faff getting things in an emulator-friendly format...)

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Re: Second Processor Elite - How did it work?

Postby MartinB » Sat Aug 20, 2016 6:44 am

Tom wrote:Also - needs the demo programs putting on an SSD. I use John Kortink's 65Link, so it's a faff getting things in an emulator-friendly format...

Do you just mean putting the listings on the linked page on to an emulator-loadable ssd image as BASIC programs? If so, it can be simply done with BeebEm's Copy & Paste support. (Apologies if I've misunderstood which is quite likely!)

Tom Seddon 2P Demo code.zip
(1.64 KiB) Downloaded 25 times


2P Demos.png

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Re: Second Processor Elite - How did it work?

Postby kieranhj » Sat Aug 20, 2016 6:44 pm

tom_seddon wrote:I wrote an article about programming for the Tube: http://ffe3.com/tom/tube.html

This is the 2nd draft (same goes for the rest of the site). The technical info is sound enough, but I'm not 100% happy about the writing... but it might prove interesting anyway.

Hey Tom, this is great! Thanks for such an informative article and demos as well. Really interested in 2nd processor programing as its something that's quite unique to the BBC from the 8-bit era. Now I have no excuse for getting started. :) Pondering what might be possible with a fully loaded Master Turbo - 128k @ 2Mhz + 64k @ 3Mhz. Quite a step up from the original Model B...
Bitshifters Collective | Retro Code & Demos for BBC Micro & Acorn computers | https://bitshifters.github.io/

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Re: Second Processor Elite - How did it work?

Postby jms2 » Sun Aug 21, 2016 7:45 pm

I really enjoyed reading that Tom, thanks for writing it!

Some time ago I tried to achieve the same kind of practical understanding of the tube hardware, but I couldn't really figure it out. In particular, I found the application note almost incomprehensible. Now having read your guide, I'll be able to re-read it and hopefully understand it.

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Re: Second Processor Elite - How did it work?

Postby tricky » Mon Aug 22, 2016 9:15 am

Thanks Tom for a good read at the weekend and JGH bbc for the original work.
Now I have another project to add to the list!


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