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

[John Robertson]

Andrew Welburn wrote:

> 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


Hi Andy,

Feel like opening the package and sharing a PDF of the instructions? 
Probably includes a schematic of the mod which may help others (like me) 
figure out a simple way to improve Pod response...although it may simply 
be a kit made by Fluke based on their technical tip guide B0151 which 
has suggested mods:

(ftp) Fluke/PDFs/Training_and_Troubleshooting/B0151-Guide to 8085 
Troubleshooting.pdf

Thanks!

John :-#)#

>

> 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 :-#)#