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Midway V-Unit; How the heck do these pcbs communicate?
#381886 - 04/09/19 03:35 AM
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I am considering adding rs232 ports to this driver to enable linking for this hardware. What I need to find out is if there is any special device/hardware/chip that makes these games communicate. Race Drivin uses a SCC68681 dual asynchronous reciever/transmitter (DUART) which I don't see something like this on a Midway V-Unit pcb.
In fact...these V-Unit games have to use some form of DUART. I can prove this from a failed attempt to link two Cruis'n USAs with crap LCD monitors (game sends garbage data the other pcb(s) can't read). If only this wasn't missed.
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Re: Midway V-Unit; How the heck do these pcbs communicate?
[Re: Hydreigon]
#381987 - 04/15/19 09:34 PM
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> I am considering adding rs232 ports to this driver to enable linking for this
> hardware. What I need to find out is if there is any special device/hardware/chip
> that makes these games communicate. Race Drivin uses a SCC68681 dual asynchronous
> reciever/transmitter (DUART) which I don't see something like this on a Midway V-Unit
> pcb.
>
> In fact...these V-Unit games have to use some form of DUART. I can prove this from a
> failed attempt to link two Cruis'n USAs with crap LCD monitors (game sends garbage
> data the other pcb(s) can't read). If only this wasn't missed.
Communication between two machines is through a parallel interface. See schematic sheet 18/25, or page 70 of this pdf:
http://arcarc.xmission.com/PDF_Arcade_Ma...1_Jan_1996).pdf
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Re: Midway V-Unit; How the heck do these pcbs communicate?
[Re: Phil Bennett]
#382007 - 04/16/19 05:21 PM
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There are multiple bus transceivers I am seeing. From what I am able to find out, they communicate via an IEEE-488 8-bit parallel multi-master interface bus that somehow makes use of an DB25 connector via 26pin ribbon cable. Williams didn't do their best with communications on this hardware. I hope this isn't a pain to implement.
Long live Namco C139.
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Conclusion
[Re: Hydreigon]
#382694 - 06/07/19 04:16 AM
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My hypothesis of them communicating via the main processor may be incorrect. I can almost confirm the link is controlled by the pals at u111 and u38 and uses a parallel type connection bus. It was a nice find but I had to get someone angry in the process.
Some good news is I did end up fixing the linking problem on both Cruis'n USA machines as the ribbon connector to both pcbs were backwards so reversing them fixed the link itself but not the slave monitor issue (at least that is not directly related to the link so connection issues shouldn't be a problem).
Edited by Hydreigon (07/13/19 08:35 PM)
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