>The introductory tunes are played by a routine in the system ROM, and it
>just reads the notes from the header at the front of the cartridge.
>The tunes are pretty short.

I kind of suspected that this was what is going on.

>
>I presume you _fixed_ the crossed address lines.   Some of the games
>require that they be in ROM; RAM won't work.  That's why the
>Vectrex-S100 interface has a write-disable line for the Vectrex.
>
Hmmm... I wonder if I should review the pinout on the bus.  Perhaps I've hooked
the write-disable line up incorrectly?  In order to make my cartridge, I looked
at the bus pinout (available from ftp on csus.csus.edu) and also examined the
4kb ROM connections in the prefabricated Star Trek game to verify that
everything seemed correct.  Then, I grabbed a blank cartridge, inserted a dip
socket for an 2764 (an 8k EPROM), and wired it up.  I found two wiring errors
when I was done, but went back and fixed them.  Perhaps there is still a wiring
error, though I examined it repeatedly over a period of several days.

>You might also want to make sure that the whole game fits in your ROM.
>Long games in short ROMs will flake out as you describe.

The 8k EPROMS should be able to handle all of the games except the ones with
the extra RAM on the cartridges.  BTW, does anyone remember which games NEED
the extra RAM?  Some people e-mailed and mentioned this to me or inquired if I
knew which ones do.
>
>BTW, it's been so long since I've run this stuff that I don't remember
>if the Bach thing has the dynamic pitch/duration graph that I wrote.  I
>vaguely recall that it doesn't, in which case the "game" isn't really
>executable at all.  (It might have been one of the early tests I did,
>and when the tune ends it displays the character set.  Thrilling.)
>--
Don't sweat it... it's cool of you to post a reply!  Thanks for the
information!

--thomas--