If you like your submarine simulations fast, arcadey,...

Any discussions related to the creation of new hardware or software for the ZX80 or ZX81
schombi
Posts: 19
Joined: Thu May 05, 2016 6:43 am

Re: If you like your submarine simulations fast, arcadey,...

Post by schombi » Thu Mar 29, 2018 8:38 pm

I have an update. It´s clear that the PSU is not the bad guy and it´s also clear that the UDG4rZXpand is not defective - the reason for the glitches and the vertical lines is still a mystery to me.

I first tried two other PSUs - no change.

I first tried an unmodified ZX81 on a super-old television and there was neither graphical glitches nor vertical lines.
udg0.jpg
udg1.jpg
udg2.jpg

schombi
Posts: 19
Joined: Thu May 05, 2016 6:43 am

Re: If you like your submarine simulations fast, arcadey,...

Post by schombi » Thu Mar 29, 2018 8:39 pm

I then tried the ZX81 equipped with the ZX8-CB on a different monitor - same result as yesterday.
udg3.jpg
udg4.jpg

sirmorris
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Joined: Thu May 08, 2008 5:45 pm

Re: If you like your submarine simulations fast, arcadey,...

Post by sirmorris » Thu Mar 29, 2018 8:59 pm

I think the zx8-ccb might need a tiny tweak. The pixel scroll routine changes the horizontal sync timing and perhaps this is out of spec for the ccb's current adjustment.

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Andy Rea
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Joined: Fri May 09, 2008 2:48 pm
Location: notts UK

Re: If you like your submarine simulations fast, arcadey,...

Post by Andy Rea » Thu Mar 29, 2018 9:01 pm

Well that is most odd, I can't imagine how the zx8-cb could cause this weirdness... Only other thing I can think is maybe the 2 zx81's have different ULA' S and somehow this causes some kind of comparability problem.

The question is do I need to do anything, so that you can use the UDG board on all your zeddys

And for future builds to try an prevent a repeat situation.

Thanks for the update, I shall keep the gears in my head grinding and see if I can duplicate the problem.

Regards Andy
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum

schombi
Posts: 19
Joined: Thu May 05, 2016 6:43 am

Re: If you like your submarine simulations fast, arcadey,...

Post by schombi » Thu Mar 29, 2018 10:14 pm

Thanks Andy! It would be great if the board worked on any Zeddy. Nevertheless, a great piece of hardware and a cool game. Unbelievable what can be achieved these days.

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PokeMon
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Joined: Sat Sep 17, 2011 6:48 pm

Re: If you like your submarine simulations fast, arcadey,...

Post by PokeMon » Sun Apr 01, 2018 3:26 pm

Maybe possible to post a better resolution picture here with the normal screen (how it should be) and what is different with ZX8-CCB.
I can not see much from these pics, sorry. Just a white line in between.

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Andy Rea
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Joined: Fri May 09, 2008 2:48 pm
Location: notts UK

Re: If you like your submarine simulations fast, arcadey,...

Post by Andy Rea » Sun Apr 01, 2018 7:24 pm

i have an idea hat may be going on, i have looked closely at the first set of images and it sure looks like the internal line counter ( of my UDG board ) is out of sync with the ZX81, in my mind ( although i need to check the verilog and perhaps re-run some simulations ) it can be one of 2 things... very noisy clock signal at the ZX81 edge connector, or which i think is more likely some borderline timing issue in my logic that happens to work in most cases BUT not all as your system has shown.

my aim is that by the end of this week to have a new logic in place that hopefully will negate this issue. i have at time been able to duplicate such behavior on a few occasions, but no sooner do i turn to my test equipment the issue ceases. it is most frustrating. however i know my clock signal is clean which is why i am leaning towards it been a bad logic implementation.

still grinding the head gears

regards Andy
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum

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