Sparkly pixels
Posted: Wed Jan 22, 2020 11:46 pm
So I have now had a number of zeddies with ‘sparkly pixels’, by this I mean that the screen shows occasional flickering and small groups of pixels randomly appearing where they should not.
In the past changing the ROM has sorted this. I now have an interesting one:
1) With the original ROM and no ‘spand the picture is rock solid. With the ‘spand it goes sparkly.
2) With a different ROM it is sparkly without the ‘spand but rock solid with it plugged in!
The zeddy in question has a vLA81 ULA in it and 32K of RAM.
Is there a scientific explanation for this or is my house built on an old native American grave yard (unlikely given that I am in the UK)?
I assume that because the character information for the screen is being read from the ROM if there are any issues that would affect the output.
One thing I have noted is that I currently have the second ROM plugged in so the screen is not stable without the ‘spand. If I load one of Dr Beeps amazing 1K hi res wonders onto the zeddy the screen is fine! Is this because the ROM is mostly not being looked at?
I guess the next question is where can I get a reasonably priced ’new’ ROMs from on a regular basis? By this I mean a modern one or at the least a recently burnt EPROM.
Any information appreciated!
Thanks
Lardo
In the past changing the ROM has sorted this. I now have an interesting one:
1) With the original ROM and no ‘spand the picture is rock solid. With the ‘spand it goes sparkly.
2) With a different ROM it is sparkly without the ‘spand but rock solid with it plugged in!
The zeddy in question has a vLA81 ULA in it and 32K of RAM.
Is there a scientific explanation for this or is my house built on an old native American grave yard (unlikely given that I am in the UK)?
I assume that because the character information for the screen is being read from the ROM if there are any issues that would affect the output.
One thing I have noted is that I currently have the second ROM plugged in so the screen is not stable without the ‘spand. If I load one of Dr Beeps amazing 1K hi res wonders onto the zeddy the screen is fine! Is this because the ROM is mostly not being looked at?
I guess the next question is where can I get a reasonably priced ’new’ ROMs from on a regular basis? By this I mean a modern one or at the least a recently burnt EPROM.
Any information appreciated!
Thanks
Lardo