[Techtoolslist] Another midway 8080 and pod (space invaders deluxe) question
Alex Yeckley
ayeckley at sierralobo.com
Mon Jun 30 15:11:50 EDT 2014
> 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 at elektronforge.com
www.elektronforge.com
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