It is currently Sun Sep 26, 2021 1:46 pm


All times are UTC [ DST ]




Post new topic Reply to topic  [ 1 post ] 
Author Message
 Post subject: Dragon's Lair Rom made for Rev. A Logic won't work on DAPHNE
PostPosted: Mon Jul 07, 2014 7:45 am 
DAPHNE Tester
DAPHNE Tester
User avatar

Joined: Sun May 12, 2002 8:37 pm
Posts: 183
Location: Yuma, Arizona
Hi,

I am making this post hoping that sometime in the future that this problem can be addressed and fixed on DAPHNE.

Serial #1 Beta Rom Set, Beta 2 Rom Set, & Rev. A - C Rom Set don't sync with the Video while playing them on DAPHNE. But this is not because they were made to only be used with a PR-7820 Laser Disc Player. Actually, it's because they were made to be used with a Rev. A Logic, only. The Rev. A Logic seems to run it's RTC Real Time Clock a bit slower then a Rev. C Logic. This is why the Roms described above don't work correctly. DAPHNE's RTC is based upon the Rev. C Logic. For these Roms to work correctly, DAPHNE will need to emulate the Rev. A RTC for these Roms to work correctly.

Below is the info. on what the differences are between the RTC of both of the Logic Boards:

In Rev. A Logic Boards Interrupts occurring at a rate of approximately 33 milliseconds are required to keep the Z80 in sync with the Laser Disc Player. The signal RTC+ (REAL TIME CLOCK) at U26-11 is a square wave with a 33 millisecond period. In Rev. C Logic Boards, U6 and U13 are cascaded to form a 16-Bit binary counter. The output of this counter circuit. U6-6 is a 33 millisecond square wave.

I'm not sure what this above means, but I believe it has something to do with why the Sync between the Game and the Video using these Roms that were made to be used with the Rev. A Logic and not the Rev. C Logic. And because DAPHNE was based upon the Rev. C Logic this is why DAPHNE does not work correctly with these Roms, either.

Yours Truly,

Tony M Victorino

_________________
End of line...


Top
Offline Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 1 post ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Theme created StylerBB.net