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Talk:Contended I/O: Difference between revisions
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: Thanks, Gergely! I've had a go at this. Unfortunately, I'm working from memory here. My recollection is that ULA I/O access is delayed using {{overline|WAIT}} (note: I'm using <nowiki>{{overline|WAIT}}</nowiki> for {{overline|WAIT}} in this Wiki, not /WAIT, !WAIT, ~WAIT or ¬WAIT :-)) but that the spurious I/O contention stops the clock. Please correct me if I'm mistaken. I don't quite get why access to ULA ports between 0x4000 and 0x7fff results in less contention than non-ULA access within that some range. We could do with adding a reference to Chris Smith's book here, although I don't currently have it. [[User:Zub|Zub]] ([[User talk:Zub|talk]]) 00:25, 3 June 2015 (UTC) | : Thanks, Gergely! I've had a go at this. Unfortunately, I'm working from memory here. My recollection is that ULA I/O access is delayed using {{overline|WAIT}} (note: I'm using <nowiki>{{overline|WAIT}}</nowiki> for {{overline|WAIT}} in this Wiki, not /WAIT, !WAIT, ~WAIT or ¬WAIT :-)) but that the spurious I/O contention stops the clock. Please correct me if I'm mistaken. I don't quite get why access to ULA ports between 0x4000 and 0x7fff results in less contention than non-ULA access within that some range. We could do with adding a reference to Chris Smith's book here, although I don't currently have it. [[User:Zub|Zub]] ([[User talk:Zub|talk]]) 00:25, 3 June 2015 (UTC) | ||
:: Hmm.. as I see, the {{overline|WAIT}} pin of Z80 is not connected to ULA (e.g.: | :: Hmm.. as I see, the {{overline|WAIT}} pin of Z80 is not connected to ULA (e.g.: https://8bit.yarek.pl/computer/zx.48/2_sch.gif), so I think ULA has only one method to delay CPU: holds CPU clock signal at high level...[[User:Szaszg|szaszg]] ([[User talk:Szaszg|talk]]) 17:12, 10 June 2015 (UTC) | ||
