Robotron CPU performance in relation to marathoning?

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Robotron CPU performance in relation to marathoning?

I'll forward this 2 weeks old post by another member, "1500points", from the Twin Galaxies forums. I'd like to hear if anyone here could shed some more light on this?
(I've been thinking about wether this could be done for Defender (Williams 1980) - to create a super fast machine, without the lag and disappearing enemies. Played on the Blue/Green roms, and set to maximum difficulty (99-99), this would be a monster!)

(Link to the thread here: Robotron CPU performance in relation to marathoning? http://forums.twingalaxies.com/viewtopic.php?f=22&t=26839)


I recently acquired a Robotron which I'm trying to stabilize so Tim Nibbler McVey can start marathoning. I'm looking for some technical insight about these observations.

Background:
I know from playing 19in1 Robotron PCB and xbox 360 robotron, that those versions have some inconsistencies from the real game.
--The player moves a bit slower in relation to the enemies.
--The speed of the projectiles is a lot faster and the amount of projectiles put on screen is greater.
--On xbox the speed of the hulks is faster.
--by wave 28 the game is wickedly hard.
--personally watching Todd R. and Tim M, who are marathon level players on real robotron, they too struggle by the 20 series of waves.
--I have attributed this to running the program in a faster/more efficient processor environment.

In playing 2 real robotrons this year, and watching the Redelf million point game on youtube, I know that
--the speed of the projectiles isn't as great for the tanks, as 19-1
--the aggressiveness of the brain's projectiles is much less than 19-1
--the time it takes the brains and tanks to create projectiles is affected by the cpu performance.
--on busy screens like brain waves the cpu seriously bogs down to very slow.
--much like joust, the cpu slowdown gives you time to really pick off the enemy before they can react.
--the result is that the tank wave in the early 30 wave on real robotron is EASIER than tank wave 7 on 19in1 Robotron.

Observations on real robotron:
--I have 2 original CPUs. One came from a joust (has a service sticker from 1994 that indicates it was in a stargate at one point in time) Other is the early stargate rev b board that has jumper wires to make it compatible with later games like robotron.
--both cpu's have original parts, but some of the ram chips were faulty on one board
--the same 24 old but working 4116 ram chips in either cpu created same performance as per above. (bogs down during heavy screen enemies)
--i put in about 10 4164 converted ram chips from Real Bob Roberts. cpu performance the same
--so then i put in 2 brand new video decoder chips and 24 brand new 4116 ram chips from real bob roberts.
--hardness setting at default of 5.
--the cpu performance immediately increased so the game didn't bog down as much. the projectiles became more prolific and fast. I'd say it double the hardness level of the real game so it is more on par with 19-1 robotron on setting 1.


So how do you explain this. If the age/brand of Rom can greatly affect the performance I've observed it seriously changes the level of play needed to marathon the game.

Who has a technical explanation for these observations?

by the way, I wasn't a robotron player in the 80s. only learned it this year after hearing Eugene J. speak at the milwaukee pinball show. i'm about a wave 28 player on 19 in 1 robotron. I've hit wave 58 on real robotron. same skills but greatly different outcomes depending on the game platform.
 
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First, your observations compared to the 19-1 and XBOX are irrelevant (As noted at TG.) One is an emulation platform, not using the original CPU, RAM, or anything else but ROM data; and the other is a console port, which historically, are different in behavior, coding, and ROM data than their arcade counterparts. Might as well be playing a different game altogether ;)

Not being a WMS vid man, I don't know what specific video decoders you replaced and with what, but I think the RAM replacements could have the effects you describe. There are numerous different speeds of 4116 RAMs. Just offhand I can think of 4116-25, 4116-30, and 4116-40's, which all have varying response times (200ms, 300ms, 400ms). Not sure what the original speed is and whether Bob is selling (and you replaced) with that exact specification.

Another thought is that maybe TTL chip timings relax over time/use? No idea on that, but sounds reasonable.
 
Clay already provided the technical insight in his programmable pcb thread on this topic. I learned what I wanted to understand.
Robotron is driven by the CPU performance which matches what I can observe between 2 CPUs and 3 varying sets of RAM.
 
i have 3 robos. a jrok, a multi/pcb and a williams. they are totaly diferent as far as speed and adjustment. I am a player, not a tech so much, but the speed and movement is very different from each boardset
Sorry if this dont help.. Im just an advid robo player.
 
This is great hands-on insight.
Can I bother you with a question?
Is there a platform out there, other than real williams robotron that plays close to real, enough that you can play up to wave 100 with the same satisfaction as the real deal?

I'm planning on selling my real machine to a friend who loves robotron much more than me, and I'd like to find a nice newschool facsimile. What is my best choice?

i have 3 robos. a jrok, a multi/pcb and a williams. they are totaly diferent as far as speed and adjustment. I am a player, not a tech so much, but the speed and movement is very different from each boardset
Sorry if this dont help.. Im just an advid robo player.
 
MarkH,

If you find yourself down in the Dallas area give me a shout and you can swing by the house and try the JROK board in my game room.

As for the original game board, it'd be interesting to try the Hitachi 6803 CPU to see if it speeds it up a bit. It's a pin-compatible chip with some restructuring and new op-codes. (Of course, the game would never take advantage of the op-codes without recompiling)
 
First, your observations compared to the 19-1 and XBOX are irrelevant (As noted at TG.) One is an emulation platform, not using the original CPU, RAM, or anything else but ROM data; and the other is a console port, which historically, are different in behavior, coding, and ROM data than their arcade counterparts. Might as well be playing a different game altogether ;)

Emulators ALWAYS feel slightly off compared with original hardware . Now I understand why , because of using a different CPU , RAM .

If you don't have the original hardware to compare side by side , it can sometimes be hard to tell the differences . But every time I've played orignal hardware next to an emulator the differences are clear . Usually the controls feel slightly slower with the emulator , but now I see it could probably be the better CPU running the enemies faster making it harder than the original .

This is why I gave up on all emulators , your not playing the game how it originally played so whats the point ? Its harder because the timing is off .
 
i have 3 robos. a jrok, a multi/pcb and a williams. they are totaly diferent as far as speed and adjustment. I am a player, not a tech so much, but the speed and movement is very different from each boardset
Sorry if this dont help.. Im just an advid robo player.

If there's a difference in gameplay between my PCB and an original WMS board, then they're either running different ROM revisions or they're not configured the same in the setup.

- James
 
The only point of difference that I have found on Williams boards is the crystal. A few times I have found where somebody replaced the crystal with slightly different crystals (the original crystal is 12.000MHz), probably a quick operator "fix". And several times where I was getting strange video output because of corrosion on the crystal case, changing the frequency. Everything on the Williams boards is controlled by that crystal and the clocks that are divided down from it.

ken
 
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