On Thursday 22 June 2017, 20:01:29 Gerrit Heitsch <firstname.lastname@example.org> wrote: > On 06/22/2017 07:36 PM, email@example.com wrote: > >> On 2015-10-13, at 07:48, Gerrit Heitsch <firstname.lastname@example.org> > >> wrote: > >> > >> At the end of 1986, Commodore changed the process from NMOS to HMOS-II. > >> For a short while, some CIAs were labeled '8521R0' but then they went > >> back to the '6526' label. Usually they were also fast enough for get the > >> 'A' for 2 MHz operation. The HMOS-II-CIA also changed a bit timingwise, > >> that's where the legend originated that the 6526A behaves differently > >> than the 6526.> > > They DO behave differently. For example my old test cart shows CIA related > > failure when using the "6526A". > Does it still show that when you use a 6526A-1 made in 1985? I expect > not. So the definig characteristic is not the 'A' but the datecode. If > the CIA was made at the end of 1986 or later, it's HMOS-II and > internally a 8521. Since HMOS-II is faster, they all tested good for 2 > MHz and go the 'A' stamped on them. Some of them were even good for 3 > MHz and got a 'B'. > > > > Do we know how exactly the differ timing-wise? I guess this is related > to what Marko wrote yesterday? > > > It's something about the timer IRQ happening one cycle earlier or later > than the NMOS version. see https://sourceforge.net/p/vice-emu/code/HEAD/tree/testprogs/CIA/irqdelay/ -- http://www.hitmen-console.org http://magicdisk.untergrund.net http://www.pokefinder.org http://ar.pokefinder.org Ich hätte natürlich nichts gegen ein paar kostenlose Reisen mit Koks und Nutten, aber dazu müsste ich erst Politiker, Unternehmer oder Lobbyist werden. Dazu bin ich leider zu ehrlich. <C64Doc> Message was sent through the cbm-hackers mailing listReceived on 2017-06-22 19:02:48
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