Arx816 & EghtyOne problem...

Discussion about ZX80 / ZX81 Software
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user@lab1
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Arx816 & EghtyOne problem...

Post by user@lab1 »

Hi.
I tried to run on EightyOne, the demo ARX816 downloaded from here:
http://homepage.ntlworld.com/deborah.cl ... grams.html
I set EightyOne to 16K of RAM, and enabled the RAM in the area between 8-16K, but at the end of LOAD, EightyOne goes into reset. :?
Has anyone else had this problem?

Mic.
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Andy Rea
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Re: Arx816 & EghtyOne problem...

Post by Andy Rea »

Erm... don't know however i can tell you that it was only ever tested with Eightyone version 0.42(Test Z) i long forgot about this mod, and eightyone has moved on a little,

Regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
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user@lab1
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Re: Arx816 & EghtyOne problem...

Post by user@lab1 »

Hi Andy.
I also tried with EightyOne v0.42 (Test Z), same result. :(
Maybe I'm missing something?

Mic.
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Andy Rea
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Re: Arx816 & EghtyOne problem...

Post by Andy Rea »

Very odd indeed, i have also downloaded 0.42Z and guess what.... doesn't work.

dive in deeper, seems like the ram ghosting behavior has changed somehow between now and then if you trace the m/c by single stepping during video routine it is not executing the RET as it should.

Good / bad news down load 0.42 from here http://www.aptanet.org/eightyone/downloads/archive/ that works.

so for this to work on real hardware the 8 - 16K ram has to be ghosted properly at 40 - 48 K region.

regards andy

EDIT :- Man thought i was cracking up, at first i couldn't get it to run on my 20Mhz uber zeddy but a few configuration poke and et viola http://youtu.be/JxmfgFEWReU
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stefano
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Re: Arx816 & EghtyOne problem...

Post by stefano »

Thank you for the hint.. I tried to help and bumped into the same problem !

(20 mhz.. cool, but as usually code runs only when the screen is not beig refreshed, right ?, it is probably equivalent to little more tha 4 mhz, if so).
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Andy Rea
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Re: Arx816 & EghtyOne problem...

Post by Andy Rea »

Yes stefano, you are correct it automatically reverts to the 3.25Mhz ( actually 3.33Mhz [ 40Mhz osc divided by 12 ] ) during video generation, are you familiar with the program CLCKFREQ.P by Carlo Delhez, it measures zx81 performance based on number of display frames taken to carry out a given task. my results are :-

233 frames vs 1863 for a standard ZX81
speed of 799.6%
effective clokc 6.4Mhz

regards Andy
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stefano
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Re: Arx816 & EghtyOne problem...

Post by stefano »

Not bad, with such a fast clock you can get a relevant boost by making the visible area thinner.
Even the ARX mode slowness is not a problem anymore.. is it the real reason for your project ? :mrgreen:
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Andy Rea
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Re: Arx816 & EghtyOne problem...

Post by Andy Rea »

ARX was developed very early on in my rediscovery of the world of ZX81, when i was tinkering with UDG's i just wondered if it was possible to utilise UDG ram in such a way as to obtain full hi-res. it was never meant as a serious hi-res mode, the driver could be improved somewhat with the removal of the huge delay at the begining, and if the MC is run in main memory ( line 0 rem statment ) i see no reason why it can't work on EIGHTYONE again

regards Andy
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user@lab1
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Re: Arx816 & EghtyOne problem...

Post by user@lab1 »

Good / bad news down load 0.42 from here...
Also I have done the same test ... :-)
I also tried it on a real ZX81-16K with external 8K expansion (2000-3FFF), but it did not work.
I suppose that ARX816 requires the 8K internal modification to work...
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stefano
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Re: Arx816 & EghtyOne problem...

Post by stefano »

I'm sure the ARX816 code works on EightyOne. This specific code seems to have something different.
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