RE: Bizarre Tailgunner (2) Experience

G'day Zonn (and all),

Excellent summary of neat (and precise) arcade trivia. So let's say we
disable the wait state generator on the Cinematronics platform so that
those awesome new games are possible. Does the speed (slew rate?) of
the monitor become the next bottle neck, since more complicated games
often have more objects?

So am I out in lala-land if I pose the question of a "universal I/O"
card that makes use of modems to communicate between two games? In the
most basic form woudl this be the equivalent to a PC's serial port? I'm
not limitting this question to just the Cinematronics platform. I'd be
much more interested in having this for the Sega XY platform (where
adding another card to the cage isn't impossible).

                Steven S Ozdemir
                sso@dsc.com

>----------
>From: Zonn[SMTP:zonn@concentric.net]
>Sent: Thursday, August 21, 1997 1:45 PM
>To: vectorlist@goonsquad.spies.com
>Subject: RE: Bizarre Tailgunner (2) Experience
>
>At 09:05 AM 8/21/97 -0700, you wrote:
>>G'day folks,
>>
>>In my experience EPROM speed is quite important for Cinematronics games.
>> I found out from my experience that I can slap any 2732 or larger EPROM
>>into a Cinematronics board with no troubles! However, If I tried 2716
>>only one in eight were fast enough (due to the random collection of
>>2716's that I had access to). How does the speed of 2532's compare to
>>2732's? I know I've used some 2532's in the past with no troubles.
>>
>>Again, I emphasize that my experience is limitted to whatever EPROMs
>>that I've run across. Maybe I just always had fast EPROMs at my
>>disposal?
>
>Many of the C-CPU instructions executed in one 5mhz cycle, which would give
>you 200ns access time -- way beyond the capabilities of the ROMs at the
>time. By using two EPROMs and alternating back and forth between the two,
>you can run at the same speed using only 400ns memory. Which is why
>Cinematronics have EVEN and ODD ROMs. It doesn't have a 16 bit bus, but
>instead by accessing alternate ROMs you can give the ROMs twice as long to
>retrieve their data.
>Still, if too many single cycled instructions are executed in a row you
>would need 400ns memory, still too fast for most memory at the time, so
>Larry (remember poor ol' Larry?) came up with a wait state generator that
>will insert an extra cycle if ever the memory is accessed in less that three
>cycles.
>
>The design was clever and used a counter and a lookup PROM to determine when
>a wait state is needed.
>
>So that leaves you with the need for 600ns ROMs. Within the range of the
>EPROMs of the day, most were rated between 450-550ns, but I can see some of
>your older ones not even making this spec.
>
>The newer EPROMs run much faster, and if you wanted you could defeat the
>wait state generator, to to allow you to write more complicated games in the
>future (now there's a market: Software that only runs on a C-CPU with the
>wait states disabled!).
>
>Disabling the wait state generator wouldn't effect the speed of the current
>games since they're controlled using an external timer, not by counting
>cycles (Well it might mess up the pretty sparkling sun in Space War, since
>that was done using software timing.)
>
>And there ya go, your dose of Arcade Trivia for today...
>
>-Zonn
>
>
Received on Thu Aug 21 11:52:07 1997