ZX81 high res display

aowen · Post by **aowen** » Mon Jul 05, 2010 6:07 pm

I've been thinking about this since I saw a demo at the VCF. Do we have support for the software only high-res mode of the ZX81 in z88dk? I mean the one which requires 16K of RAM and probably involves PUSHing bitmap data to the screen at a ludicrous rate (and where you lose the first column of the screen)?

Post by **stefano** » Wed Jul 07, 2010 4:50 pm

If you are referring to that mode not requiring hardware changes at all but some RAM space the answer is no, for now. That weird pseudo-hrg mode has heavy limits and I still haven't found an elegant way to fit it in the current CRT0 structure (i.e. the Memotech HRG lib tweaks the text mode interrupt handler, and this is the only case in which, for hardware reasons, we loose the first column of video).. I'm convinced that it should be more useful a mid-rez based on those expansions capable of characters redefinitions.

Otherwise, if adding just two diodes to the rampack is acceptable:
http://www.z88dk.org/wiki/doku.php?id=p ... rtup_modes