[Techtoolslist] RASTER: FW: Using 8080 pod on Midway 8080 boards (Space Invaders)

[Andrew Welburn]

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 at flippers.com

>> [mailto:techtoolslist-bounces at flippers.com] On Behalf Of John Robertson

>> Sent: Sunday, February 17, 2013 7:23 PM

>> To: techtoolslist at 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 at 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 :-#)#

>>

>> _______________________________________________

>> Techtoolslist mailing list

>> Techtoolslist at flippers.com

>> http://seven.pairlist.net/mailman/listinfo/techtoolslist

>> FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment

>> Archive site: http://seven.pairlist.net/pipermail/techtoolslist/

>>

>> ---------------------------------------------------------------------------

>>

>> ** Unsubscribe, subscribe, or view the archives at

>> http://www.vectorlist.org

>> ** Please direct other questions, comments, or problems to

>> chris at westnet.com

>>

>

>

> _______________________________________________

> Techtoolslist mailing list

> Techtoolslist at flippers.com

> http://seven.pairlist.net/mailman/listinfo/techtoolslist

> FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment

> Archive site: http://seven.pairlist.net/pipermail/techtoolslist/

>