RE: Bizarre Tailgunner (2) Experience

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?

                Steven S Ozdemir
                sso@dsc.com

>----------
>From: Zonn[SMTP:zonn@concentric.net]
>Sent: Wednesday, August 20, 1997 8:10 PM
>To: vectorlist@goonsquad.spies.com
>Subject: Re: Bizarre Tailgunner (2) Experience
>
>At 04:50 PM 8/20/97 CDT, you wrote:
>>
>>(was: RE: interesting coincidence..)
>>
>>In message "interesting coincidence..", you write:
>>
>>> >I haven't done any ROM comparisons for Tailgunner.
>>
>>My TG2 originally used 2708s so I converted it to use 2532s by reading
>>in the 2708s and combining the images. Once I had figured the original
>>addressing and mapped the various locations, I burned the new roms. All
>>seemed to be ok as the game powered up and entered the attract mode.
>>However, once I started playing the game it was apparent that something
>>was very wrong.
>>
>>First I noticed a small twitch in the approaching enemies. Their movement
>>seemed to become more and more jerky, until the ships would actually dis-
>>appear from one location and reappear somewhere else. The next major shock
>>was to see the enemies start going backwards! As you know they *always*
>>move forward. The last oddity was the shield. Instead of being geometric,
>>the shield kind of bends into an oval shape. Really weird!
>>
>>Anyway, my point; thinking I had somehow managed to corrupt my rom images
>>I double checked them against the TG roms someone sent me in a file called
>>CinemROMS.tar. I don't know if the roms in that file were taken from a TG
>>or a TG2. However, the roms from my TG2 compared perfectly with the roms in
>>the file.
>>
>>Incidently, the roms I burned showed the correct checksum and even compare
>>with no errors to the rom files. Finally, I burned a new set and they worked
>>fine. Although that was years ago, I saved the chips and occasionally put
>>them in the game for a laugh. It also helps increase the challenge!
>
>Sounds like you have slow ROMs. The ROM readers read ROMs at an very slow
>rate, whereas running them in the game runs them at full speed. It sounds
>like some data just can't get there fast enough. So they checksum and
>compare ok in the ROM reader but don't play correctly.
>
>It's amazing the game continued to run though, it wouldn't take but one
>corrupted opcode to crash the game. There is a table lookup instruction
>that allows the game code to access ROM tables, it plays a lot with the ROM
>address bus. Maybe your ROMs are just at the verge that allows normal
>sequential access to work, but table lookups sometimes get scrambled. Or
>maybe I have no idea why your ROMs do what they do and I'm pulling ideas as
>fast as I can type out of thin air. If I were a betting man I'd bet on the
>latter...
>>
>>What other really bizarre things have you seen come from a cinematronics
>>game?
>>
>>> Does anybody with an easily accessible Tailgunner II want to do a ROM
>compare?
>>
>>I have the TG2 files if you want to compare them.
>
>If you compared your ROMs with those on the net, then I'm sure your ROMs
>match the standare TG ROMs. 1) It's unlikely that the ROMs on the net are
>from a TG2, and 2) If they are from a TG2, then a TG2 matches a standard TG
>since I've compared the ROMs from my TG with the ones on the net (actually
>many copies of the many differently named ROMs on the net)
>
>So thanks Mark, I think you've answered the TG / TG2 question.
>
>I someone is *really* not convinced, you can send me your images and I'll
>compare them with my known TG set, or vica versa.
>
>-Zonn
>
>
Received on Thu Aug 21 09:07:39 1997