Re: 128DCR lockups

From: Daniel V. Mackey <>
Date: Thu, 17 Sep 2015 18:50:10 -0400
Message-Id: <>
At 06:17 PM 9/17/2015, you wrote:
>Hi all,
>I proudly own 3 128DCR's just last year I 
>attached my V2 Super CPU MMU adapter and its 
>jumper clips clip to certain pins on the 8502 
>CPU of course using the CMD installation guide.
>This all seemed to work okay I had the computer 
>on for a few hours and then out of the blue¬
>some random fine dots appeared on the screen and it locked up completely.
>This was intermittent so I never knew when computer would lockup. ¬
>I asked Ray Carlsen about this he suggested 
>isolating each chip with a piece of thick 
>cardboard heat each chip this way and maybe the lockup might happen.
>I heated the MMU chip BAM it locked up the same way.
>I removed the MMU chip out of the MMU adapter, 
>installed MMU chip in MB socket heated¬
>again, Bam same lockup.
>I robbed an MMU chip out of a dead Flat 128 
>installed in socket heated it but finally no 
>lockup this time.¬  I wonder if the Super CPU 
>MMU adapter if that is installed wrong if this 
>might damage the MMU chip.¬  I had always 
>installed mine correctly anyway and rechecked¬
>a few more times before applying any power.
>I just wanted to pass this info on maybe some 
>know of isolating chips in this way
>this sure made my day to figure this problem out. ¬
>Im just wondering if anybody else has had the same MMU problem or bad MMU,¬
>intermittent lockups?
>I like the V2 SCPU for the 128 but it seems to 
>be a bugger to get it to run correctly I have 
>always had problems occur with the MMU adapter 
>itself, the Super CPU unit has always¬
>performed good.
>Positive SUPER CPU comments only I really like 
>the unit, but really concerned about the MMU 
>design.¬  The MMU I believe has something to do 
>with the timing on the MMU so the¬
>Super CPU can run in 128 mode I may have missed other details.
>Terry Raymond

I soldered the wires from the MMU board directly 
to the CPU, I had no more problems. Those clips suck!


QUOTE : "A Clean bench is a sign of a weak mind."

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Received on 2015-09-17 23:00:07

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