Re: RASTER: FW: Using 8080 pod on Midway 8080 boards (Space Invaders)

Just to round this discussion off.. i have this adapter (unused) :

http://www.andysarcade.net/pix/9000A-8085uutadapt.JPG

to quote:
"Improves clock signal quality between UUT and the pod by reducing the
effects of capacitive loading"

  Proof that there are instances where a pod wont work quite right
in-circuit. It is rare, but some circuit designs are on the edge and the
pod can tip the balance.

Andrew Welburn
http://www.andys-arcade.com

On 19/02/2013 04:12, John Robertson wrote:
> David Shoemaker wrote:
>> The pod has a -1 CPU in it which should be good to 3 mhz the board is a
>> straight 8080a which should be 2mhz. But I tried it with the CPU from
>> the
>> board just for completeness. No improvement. And the pod cpu works
>> fine in
>> game.
>>
>> I have one board that will at least start up partially with the pod,
>> but two
>> others that just error on Run UUT.
>>
>> It is really inconsistent. I think the way the memory system works the
>> fluke
>> ram test will never work (strange timing and sync to get the game board
>> rotation stuff to coordinate access to ram).
>>
>> I have two of these pods, both use the flat ribbon. I tried subbing a
>> twisted ribbon from an 8085 pod but the pod fails self test (I suspect
>> the
>> ground lead is mucking with something).
>>
>
> I was testing an 8080 board only last year, but didn't get it booting,
> so it is sitting waiting for me to take another go. I can't recall doing
> the "Run" on any of the 8080 boards recently so haven't any better ideas
> at the moment...
>
> Perhaps someone else here has a suggestion?
>
> John :-#)#
>> -----Original Message-----
>> From: techtoolslist-bounces@flippers.com
>> [mailto:techtoolslist-bounces@flippers.com] On Behalf Of John Robertson
>> Sent: Sunday, February 17, 2013 7:23 PM
>> To: techtoolslist@flippers.com
>> Subject: Re: [Techtoolslist] RASTER: FW: Using 8080 pod on Midway 8080
>> boards (Space Invaders)
>>
>> David Shoemaker wrote:
>>> So my mails to tech tools don't appear to be getting through. But
>>> this is a raster game so I will cross the stream.
>>>
>>>
>>>
>>> *From:* David Shoemaker [mailto:davids@oz.net]
>>> *Sent:* Saturday, February 16, 2013 12:20 AM
>>> *To:* 'Technical Tools Mail List'
>>> *Subject:* Using 8080 pod on Midway 8080 boards?
>>>
>>>
>>>
>>> I have a fully working space invaders board which when I hook the pod
>>> up to and do Run UUT doesn't, it starts up and crashes.
>>>
>>>
>>>
>>> Pod passes self test.
>>>
>>>
>>>
>>> Anyone ever done this?
>>>
>>>
>>>
>>> David
>>>
>> Try a faster 8080 CPU in the pod, or try substituting the 8080 from
>> the game
>> in place of the pod CPU. It is possible the CPU is bad or slower than the
>> system can handle.
>>
>> Do you have the flat ribbon cable from the pod to the CPU socket or the
>> twisted pair cable? The twisted pair cable handles noise better and will
>> work in situations when the simple flat cable won't, plus it can be
>> longer
>> as a result.
>>
>> David, I have no idea why this did not show up in TTL - you are
>> subscribed
>> under the same email address as you posted here. I haven't seen any
>> bounces
>> for your email address.
>>
>> John :-#)#
>>
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>>
>
>
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Received on Mon Mar 4 08:29:58 2013