VECTORLIST - The Mailing List For The Technical Discussion of Vector-Based Arcade Games

October_1999
RE: vector programming...


From: Clay Cowgill ( )
Date: Mon Oct 04 1999 - 17:20:42 CDT


> Do you have anything that gives an insight on how the EEPROM functions
> work for Tempest? The Mathbox?
>
I can help out on the EEPROM. I actually mapped out what all goes where...
I'll look for the doc at home. (I had to figure it out to leech some EEPROM
space for the V-breakout highscore in the Tempest Multigame.

I have some sample code for reading and writing to the EEPROM too if you
want it...

> Also, Clay Cowgill mentioned a strange AVG routine that was not documented
> at: http://www.kfu.com/~nsayer/games/vecops.txt . Anything you can add to
> that document?
>
MAME seemed to goof up on some types of vector draws-- it read a high-bit as
a sign instead of the MSB of the length. The thing I couldn't figure out
 from Jess' doc was some sort of implied subroutine call or something. The
Atari vector ROMs used it-- I wrote a little vector disassembler based on
Jess' info that automatically mapped the Tempest character ROMs (I suppose I
should give you that too) and there were some routines that my disassembler
would miss. It seemed as though a "return" wasn't always a return and
sometimes it would automagically go to the next routine in VROM. Weird
stuff.)

-Clay


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