ZX81 Aszmic ROM Display Problem

[EeDee]

Hi All
I've been trying alternate ROMs on the ZX81 Core with varying success. The ROM I would like to use most of all, though, is Aszmic (Assembler ROM I suppose). It loads and it does work but the screen image is skewed quite badly thus making it unusable.
Has anyone tried the ROM and found a solution to the problem?

[fierman]

The issue was present with the physical rom as well apparently. Not as bad as it is in the FPGA core, but still. ( https://forum.tlienhard.com/TS1000/www. ... 401388.htm )
And some emulators had the problem too. ( https://sinclairzxworld.com/viewtopic.php?t=4634 )

Perhaps worth creating an issue for this one in the repo ?

[EeDee]

Thank you for that @fiermann. Very helpful as It helps me to work out what is NOT the problem and thus avoid blind alleys