Please Explain Missile Command Board Revisions

XXI21

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Hey man if you wanted me to post today just ask! ;)

Atari produced four different 'versions' of MC board. (The 'version' term IMHO is a misnomer because small changes to a hardware baseline are usually called 'revision'. But anyway.) Versions -01 and -03 use 11 program PROMs - ten 2708's (1kx8) and one 2716 (2kx8). Versions -02 and -04 use six 2716's. I'm guessing that Atari wanted to have the option of using either device depending on device cost and availability.

Versions -01 and -02 call out PROMs with the -1 revision (my word) of CPU code. Versions -03 and -04 call out the -2 revision. I'm guessing -1 was a release baseline above beta. The -2 version was supposed to fix a bug having to do with gameplay in cocktail mode although I'm not sure what the fix was. I seem to remember at one point trying cocktail mode with the -1 PROMs and it seemed to work fine. But it was serious enough that Atari felt the need to release a new rev, so it was probably something I missed. :)

The difference in versions also means a difference in PWB hardware configuration in order to support the two different PROMs. This is accomplished through jumpers on the card near the EPROMs. Because the 2716's are double in size, they have an extra address bit (10) at pin 19 where the 2708's have +12V. Also the 2708's have -5V assigned to pin 23 where the 2716's have a programming voltage (+5V for normal operation). Last but not least are the selection of the EPROM chip selects. There are 11 different chip selects available derived from the address decoding circuitry. For the -01 and -03 versions these correspond one to each EPROM device. For the -02 and -04 versions, each two chip selects adjacent in memory are combined into one for each 2716. That is except for one. Remember that on -01 and -03's there's already one 2716, so that chip select isn't modified. For all the rest, there are jumper locations to select between the two chip select schemes.

So does that answer your question? :D
 
I mean, should I care which revision it is? Reliability factor? Bugs?
You know I'm a player... Do you have a preference?

I prefer the SMA multikit, hands down. It eliminates the need for the EPROMs and sockets, and plus it's just win! :cool:

The -02 and -04 versions are preferrable because they only use 6 sockets and they don't use +12V which means you can run either an AR-II rev-02 or -03 with it and not have to worry about loading them too much. The -01 and -03 versions are excellent candidates for the SMA kit BTW! :)

The version numbers should be written in pen on the boards. look and you should see a '-03' or '-04'. Those seem to be the most common.

If you're still not sure, post pictures and we can help. :D
 
If it helps, if you have either versions -01 and -02 with the -1 revision of CPU code, DIP4 @ R8 doesn't function (trackball speed). If you're using an upright (and I'm pretty sure you are) then no problem.

-2 revision of CPU code introduced the ability to switch DIP4 @ R8 to ON - to indicate that the smaller mini-trackball was being used. I'm not entirely convinced it was a problem with the cocktail (I too used the -1 revision of code im my cocktail without any issues). My personal pet theory is that swith DIP4 @ R8 was introduced when the cabaret Missile Command rolled off the production lines. I think this because the -1 rev always knew when it was sat in a cocktail because of the second set of controls plugged into the board (and that as well as screen flipping, the board also took account of the mini trackball). Wouldn't have happened in a cabaret though as only one set of controls would be present.

Like I say though - that's pure speculation on my part.
 
That's a good a theory as any I've heard. If you could verify that the cabarets were produced after the uprights and cocktails, I'd say we have a plausible explanation.

If it helps, if you have either versions -01 and -02 with the -1 revision of CPU code, DIP4 @ R8 doesn't function (trackball speed). If you're using an upright (and I'm pretty sure you are) then no problem.

-2 revision of CPU code introduced the ability to switch DIP4 @ R8 to ON - to indicate that the smaller mini-trackball was being used. I'm not entirely convinced it was a problem with the cocktail (I too used the -1 revision of code im my cocktail without any issues). My personal pet theory is that swith DIP4 @ R8 was introduced when the cabaret Missile Command rolled off the production lines. I think this because the -1 rev always knew when it was sat in a cocktail because of the second set of controls plugged into the board (and that as well as screen flipping, the board also took account of the mini trackball). Wouldn't have happened in a cabaret though as only one set of controls would be present.

Like I say though - that's pure speculation on my part.
 
Not sure if it counts as verification, but I have here a PDF of internal Atari document that lists `Atari Coin-Op Project Priorities' as of May 1980. Shows that Missile Command upright and cocktail are already in production, whereas the cabaret is in `Pre-Production'. Like I say, not sure that counts as verification, but it at least suggests that the cabaret was on a slower production track.

I can't upload the PDF as it's slightly larger than the KLOV upload limit. Happy to email it to someone who might be able to post on forum if there's any interest.
 
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