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sorgelig / ZX_Spectrum-128K_MIST

ZX Spectrum 128K for MIST Board
GNU General Public License v2.0
31 stars 18 forks source link

Don't disable the ULA port write during turbo loading #8

Closed gyurco closed 7 years ago

sorgelig commented 7 years ago

This pull is unnecessary and too obvious. I've already did the same quickfix.

gyurco commented 7 years ago

Of course, it is obvious. But was a great conversation discovering the problem, and helped me to understand your code (and your intentions, because the harder task is to found out why a piece of code is there sometimes). Will you push your fix soon?

sorgelig commented 7 years ago

I will try. I still want to disable writing first. Just need to find some time between other projects.

sorgelig commented 7 years ago

By the way, my current development platform is MiSTer: https://github.com/MiSTer-devel/Main_MiSTer/wiki ZX core is ported there as well.

sorgelig commented 7 years ago

Ok, I've tested with write disable and found that write enable works better.

sorgelig commented 7 years ago

pushed the commit

gyurco commented 7 years ago

Looks great, and one can use a more recent Quartus release to develop I guess. And probably cheaper than Mist? Just curious, why just 3x6 bit VGA, and not 3x8? Not enough pins?

sorgelig commented 7 years ago

Main video output is HDMI which is 24bit. VGA is mostly for debugging. 99% of cores don't need more than 18bit. 80% don't need even 12bits. There is no reason to waste the GPIO. Doing 24bits for VGA will require DAC chip (otherwise why bother?) which will increase the cost and board assembly complexity which is considered DIY.