Is the /ram being selected? Chips L3 pin 12, M5 pin 4, and 6?
On Sun, Jan 23, 2011 at 2:30 AM, Dave Langley <dave2084.forums@googlemail.com> wrote:
I'm trying to fault find an asteroids board with Read/Write Problems on the vector RAM.
So far I've done the following:
The game arrived with no display and two tones indicating E2/E2 RAM Fault; I quickly traced the fault to M5 pin 11 being stuck low so the RAM was never selected.
Now the game gives two high tones and two low tones. When using my Fluke 9010A I am getting a R/W error on bits FF for all addresses in the range 4000 to 47FF. The vector ROM however gives the correct checksum (CBED) so the buses must be OK?
Does anyone have any idea where I can go from here?
-- Dave Langley--------------------------------------------------------------------------- ** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org ** Please direct other questions, comments, or problems to chris@westnet.com Received on Sun Jan 23 14:16:28 2011
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