Paged memory sound boards...

<x-flowed>Gah, there are days when I wish I fixed simple things, like rocket engines...

Currently I'm trying to figure out how to test a Williams sound board
that uses a 6809E with 172K of paged ROM memory (address bit toggled)
that is working only with some lower size ROMs, but not with the
program memory (verified!) for the particular game - Riverboat
Gambler. Bloodly black magic sound boards if you ask me!

So, the sound board (D-11578 I think is the number) will work with
Police Force sound ROMs (27256) installed, but not with either
Whirlwind or Riverboat Gambler (27512) ROM installed. Jumpers are
correct, no defective sockets, RAM is good, can select the individual
ROMs with the 6809E pod. However I don't get the Reset BONG
noise...except two separate times:

The first time was when I had placed my Bugtrap Logic Comparator on
the 74LS175 (ROM select logic) - then the sounds worked properly!
However when I replaced the suspect 175, no sounds, and when I put
the original 175 back in the (now socketed) PCB, I don't get the
sounds even with the Bugtrap the same way.

The second time I got a Reset BONG repeatedly when I first tried the
6809E pod on my 9010 - did RAM tests, BUS tests, etc, then tried RUN
UUT - then shorted the PCB Reset line and BONG! And again (Reset)
BONG (Reset) BONG...sigh, checked original CPU back in socket - no
BONG, put 6809E pod back in - no BONG!!! ARGHHHHH...

Checked BUS - fine, voltages - fine, pullups - all fine, socket
connections to ICs fine....I'm missing SOMETHING! Pulled out
Motorola's data book in the off chance that Williams engineers missed
something special about pullups on unused lines - nothing so
far...(this was the case on Game Plan MPUs about the Z80! nasty bit
of bad design there.)

I think this board is going to become a frisbee!

John :-#(#

PS, remind me to fix the description line on the email reply...

-- 
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
                  www.flippers.com
"Old pinballers never die, they just flip out"
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