Re: 'Frankenstein' Disk Drives, Done Cheap

From: Gerrit Heitsch <*gerrit_at_laosinh.s.bawue.de*> Date: Thu, 24 Apr 2014 17:20:25 +0200 Message-ID: <53592BB9.9010304@laosinh.s.bawue.de> · gerrit_at_laosinh.s.bawue.de

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?

  Gerrit

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