On Friday 25 April 2014, you wrote: > On 04/24/2014 10:51 PM, Groepaz wrote: > > On Thursday 24 April 2014, you wrote: > >> On 04/24/2014 02:06 PM, David Wood wrote: > >>> http://oms.wmhost.com/misc/C64C_VSP-fix_theory.png seems to be the > >>> trick. I was linked this via IRC. It doesn't actively search for the > >>> party, but instead latches the DRAM address before the VicII has a > >>> chance to change its mind. > >> > >> I see what it does... If I understand it right that trick will only work > >> since _CAS on the C64 has to go through the PLA. If _CAS were directly > >> connected to the DRAMs, it would fail since the additional delay of the > >> 74xx86 and the 74xx573 would cause the DRAMs to miss their column > >> address. > >> > >> Did someone figure out what exactly happens inside VIC when this problem > >> surfaces? > > > > according to jens schönfeld its a setup-and-hold timing violation. > > Yes, but why? The CPU was done with its part of the cycle a few hundred > nanoseconds before this problem happens. What can the CPU do to VIC > there that will only surface that much later? > > I would expect that no matter what the CPU does, everything inside VIC > had stabilized by then. dunno, ask jens :) its all mad wizardry to me =) -- http://www.hitmen-console.org http://magicdisk.untergrund.net http://www.pokefinder.org http://ftp.pokefinder.org Foolish man give wife grand piano. Wise man give wife upright organ. Message was sent through the cbm-hackers mailing listReceived on 2014-04-25 20:01:41
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