[TECH] Mr Do's Castle help needed

[guddler]

[ukvac] [TECH] Mr Do's Castle help needed
Hi,

I've finally taken some time to look at several boards that I have here which
are totally dead. A Mr Do's Castle and a Do Run Run (both very similar
hardware).

Both boards do exactly the same, so I'm after some advice on how to proceed.
Okay, so this description goes for both games...

Both the 4mhz, and 9.828mhz crystals are producing waveforms that look to be
correct (comparing them to a running, but glitchy Do Run Run board).

All three Z80's are resetting at an steady interval (about once a second if
that's relevent!).

Looking at the mame driver I can associate roms on the board with their
corresponding Z80's so where do I go from here?

Will it stand to reason that I need to first get data flowing from the four roms
associated with CPU 1 into and out of the 8128 memory (is this pin compatible
with 6116 BTW?) so the game will go into it's intruction cycle and then probably
display garbage? Then move onto the second cpu ang get the graphics going?

Does anyone know this hardware and is able to supply a run down on what sections
do what (if you know what I mean)??

Ta,
Gudd.

 

[LukeWells]

Re: [ukvac] [TECH] Mr Do's Castle help needed
> All three Z80's are resetting at an steady interval (about once a second
if
> that's relevent!).

thats about a typical watchdog time, doesn't tell you anything really

>
> Looking at the mame driver I can associate roms on the board with their
> corresponding Z80's so where do I go from here?
>
> Will it stand to reason that I need to first get data flowing from the
four roms
> associated with CPU 1 into and out of the 8128 memory (is this pin
compatible
> with 6116 BTW?)

I think it is actually, I remember its 2k x 8 100ns as I had to fix a board
with these not long ago

>so the game will go into it's intruction cycle and then probably
> display garbage? Then move onto the second cpu ang get the graphics going?

common sense would say that yes the main program cpu will be responsible for
the watchdog, so that is going to be your starting point, although there
could be a watchdog for each cpu, I don't know, thats something that really
needs to be checked in the schematic.

Disabling the watchdog would be a good idea, removing the capacitor that
creates the pulse would be the easiest way, but then you would have to
manually reset the cpus on power up. But that shouldnt be a problem, just
short the reset to ground on one of the cpus and they should all be
interconnected and reset as well.

> Does anyone know this hardware and is able to supply a run down on what
sections
> do what (if you know what I mean)??
>
> Ta,
> Gudd.
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>

 

[guddler]

RE: [ukvac] [TECH] Mr Do's Castle help needed
> common sense would say that yes the main program cpu will be
> responsible for the watchdog, so that is going to be your
> starting point, although there could be a watchdog for each
> cpu, I don't know, thats something that really needs to be
> checked in the schematic.

There does appear to be a single watchdog circuit for all three processors...

> Disabling the watchdog would be a good idea, removing the
> capacitor that creates the pulse would be the easiest way,
> but then you would have to manually reset the cpus on power
> up. But that shouldnt be a problem, just short the reset to
> ground on one of the cpus and they should all be
> interconnected and reset as well.

The watchdog would appear to consist of a single 556 with a bunch of resistors
and a few caps. Can't I just tie pin 9 (the output reset signal) of this IC to
5v to disable the watchdog??

Gudd.

 

[Macro]

RE: [ukvac] [TECH] Mr Do's Castle help needed
> common sense would say that yes the main program cpu will be
> responsible for the watchdog, so that is going to be your
> starting point, although there could be a watchdog for each
> cpu, I don't know, thats something that really needs to be
> checked in the schematic.

of course, some multi-cpu games have a watchdog on each CPU (like world cup
90)

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[Macro]

RE: [ukvac] [TECH] Mr Do's Castle help needed

 

[LukeWells]

Re: [ukvac] [TECH] Mr Do's Castle help needed
> The watchdog would appear to consist of a single 556 with a bunch of
> resistors
> and a few caps. Can't I just tie pin 9 (the output reset signal) of this
IC
> to
> 5v to disable the watchdog??
>

Obviously I can't see the circuit at the moment, but that should work,
although as before you'll have to manually jump start the reset line to get
things going (or start the game up with the watchdog kicking and then short
the reset to 5v)

I'd rather disconnect the watchdog, like cut pin 9 and then solder it back
after you fix the board

Luke