Posted... Hopefully it goes thru, it had pictures in it. Link is here: http://www.villagebbs.com/forum/index.php/topic,24850.msg205478.html#msg2054 78 -----Original Message----- From: Techtoolslist [mailto:techtoolslist-bounces@flippers.com] On Behalf Of John Robertson Sent: Tuesday, July 01, 2014 2:33 AM To: Technical Tools Mail List Subject: Re: [Techtoolslist] Another midway 8080 and pod (space invaders deluxe) question On 06/30/2014 7:00 PM, William Stillwell wrote:
I had this same problem on an Atari Hercules/Superman Board, I could read/write the ram, but when I did a loop random reads would fly across the screen., turned out to be a clocking issue ( I posted the repair on KLOV and VillageBBS )
I don't think midway 8080 boards use different speed clocks between ram and rom read/writes
Hi William, Do you mind posting a short copy of your Atari Superman/Hercules solution here so it can be found in a search? Thanks, John :-#)#
-----Original Message----- From: Techtoolslist [mailto:techtoolslist-bounces@flippers.com] On Behalf
Of
Rodger Boots Sent: Monday, June 30, 2014 9:45 PM To: ayeckley@sierralobo.com; Technical Tools Mail List Subject: Re: [Techtoolslist] Another midway 8080 and pod (space invaders deluxe) question
Maybe a sync problem (video system butting heads with processor---wouldn't happen in normal use). On Jun 30, 2014 2:12 PM, "Alex Yeckley" <ayeckley@sierralobo.com> wrote:
Comes back with 0xFF. Hit loop and it starts to wander all over creation.
From highest to lower probability, based on my experience. YMMV:
1) bus fight with ROM or I/O bus 2) bus transceiver(s) bad 3) genuine RAM problem 4) I/O control latch problem 5) incorrect clock phasing or enable signal threshold between the even and odd RAM banks 6) other
Any ideas on why ram would fail this way? They reportedly could suffer physical damage if the -5V (or was it the +12V) was not properly supplied. Not sure the exact failure mechanism was at the die level.
Alex ---- ayeckley@elektronforge.com www.elektronforge.com
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