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MiSTer-devel / ZX-Spectrum_MISTer

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wd1793 need delay #3

Open xolod79 opened 5 years ago

xolod79 commented 5 years ago

In the attached image there is a demo with a turbo loader attached. which works fine on the real Speccy and on emulators, but does not want to work on the FPGA implementation. After hours of debug FPGA, I discovered that without special delay between calling the 1FF3,2A53,2FC3 procedures and between calling the trdos 2F1B procedure (reading the sector) it reads garbage. And if you put a delay there, then everything goes well. (shfix.C option) trdos-bug.zip trdos-bug

sorgelig commented 5 years ago

If you already know how to fix then make a PR.

xolod79 commented 5 years ago

I don `t know what needs to be fixed. Please look in the simulator what is happening.

gyurco commented 5 years ago

Isn't it TR-DOS version specific?

xolod79 commented 5 years ago

Not specific. I try 5.03 аnd 5.04. Same effect.

sorgelig commented 5 years ago

If you want to see the Shock Megademo then there is a TAP version which works fine. As for WD1793 fix - probably it's possible to decrease the delays in the core to suit this loader but i'm not sure how it will affect other loaders.