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Tweaks timing empirically.

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This commit is contained in:
Thomas Harte 2021-03-22 23:20:49 -04:00
parent 6da099d7e1
commit d0776b58cf
1 changed files with 7 additions and 2 deletions
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9
Machines/Sinclair/ZXSpectrum/Video.hpp
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@ -79,13 +79,18 @@ template <VideoTiming timing> class Video {
//
// Contention begins four cycles before the first video fetch, so it begins at 70904. I don't currently
// know whether the four cycles is true across all models, so it's given here as convention_leadin.
//
// ... except that empirically that all seems to be two cycles off. So maybe I misunderstand what the
// contention patterns are supposed to indicate relative to MREQ? It's frustrating that all documentation
// I can find is vaguely in terms of contention patterns, and what they mean isn't well-defined in terms
// of regular Z80 signalling.
constexpr Timings result = {
.cycles_per_line = 228 * 2,
.lines_per_frame = 311,
.interrupt_time = 56543 * 2,
.interrupt_time = 56545 * 2,
.contention_leadin = 4 * 2,
.contention_leadin = 2 * 2, // TODO: is this 2? Or 4? Or... ?
.contention_duration = 129 * 2,
.delays = {