Hi all, Are the 41256 Ram that was used on C128 or way earlier? Terry Raymond On Wednesday, October 12, 2016, Gerrit Heitsch <gerrit@laosinh.s.bawue.de> wrote: > On 10/12/2016 07:34 AM, Marko Mäkelä wrote: > >> Hi Ruud, >> >> On Wed, Oct 12, 2016 at 05:15:44AM +0000, Baltissen, GJPAA (Ruud) wrote: >> >>> Hallo Gerrit, >>> >>> >>> 41256 need 8Bit refresh... >>>> >>> >>> Nope. Otherwise the Finnish's and the 64'er's 256 KB hack on the C64 >>> wouldn't >>> have worked. >>> >> >> The VIC-II in the C64 (as well as the VIC-IIe in the C128) implements an >> 8-bit refresh counter. That was proven in 1994 by the test program that >> Andreas Boose wrote, to check which memory addresses the VIC-II chip is >> reading. >> > > There was no need to prove that... VIC (and TED) _has_ to supply an 8Bit > refresh since the 64Kx4 DRAMs and some of the 4164 need it. If VIC was only > doing 7Bit, Commodore would have been limited with the 4164 they could use > and the 250466 and 250469 boards couldn't exist. > > So when replacing 4116 DRAMs with 4164, make sure what kind of refresh > your system supplies. If you don't know, use 4164 that only need 7Bit > refresh. To find out, grab the datasheet. > > Gerrit > > > > > > Message was sent through the cbm-hackers mailing list > Message was sent through the cbm-hackers mailing listReceived on 2016-10-12 20:01:10
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