Neo Geo MVS RAM locations - a preliminary document

mainman said:

So I take it you would be interested in the pics, I ask because it will be a task as it require me to disassemble the 4 and 6 slots. Will not get to it until next weekend however.

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That would be fine thanks, no rush right this moment as I'm concentrating on getting the text part of the RAM locations completed.

IronGiant said:

Eh? How would I be jerking with your time? I think my document is proof that I'm actively doing something with this little project.

Thanks for your kind offer - at the moment I'd like to stick to a clear (ie so all board text can be read), large shot of each main board (with any cartridge slots and/or plastic or metal covers removed) so that I can annotate them with a few circled areas and a bit of text just to show where the RAMs are located. werejag has offered to upload some pics of a 2slot and a 1f. The bootlegs are of interest, but not at this stage of the project (but feel free to upload them if you like).

I'll probably end up having to put these on a web site as putting them into the Word document (or a PDF) might make it too large and unwieldy.

Actually, what do others think of this - should the annotated pictures go into the main document or hosted on web site?

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I was just curious if this project was a passing interest to you or if you was going to see it through because if you are I could contribute my time.


Pictures would help locate components for people who can not follow the silk screen. Also you should also include failures outside ram failures, this will burden you for a little while as your document will be dynamic until it finally covers all bases but in the end your work could be one of the biggest contribution to the community if you want to put more of your time and heart into. As it stand so much info is scattered across the boards.

mainman said:

I was just curious if this project was a passing interest to you or if you was going to see it through because if you are I could contribute my time.

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That very much depends on how much free time that I have - so as not to confuse matters too much (and give myself too much to do) I'm doing this on a step by step basis. First part is getting the RAM locations documented. Second part is getting some decent pics of the boards that I can annotate. Third part is expanding more on the RAM and troubleshooting RAM errors (Second and Third parts are interchangeable though). In a nutshell, I'm concentrating on the RAM right now as it's a common point of failure.

Pictures would help locate components for people who can not follow the silk screen. Also you should also include failures outside ram failures, this will burden you for a little while as your document will be dynamic until it finally covers all bases but in the end your work could be one of the biggest contribution to the community if you want to put more of your time and heart into. As it stand so much info is scattered across the boards.

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Indeed it is, I'm doing my best to try and bring this all together, but one step at a time.

I can't promise that this project won't stall from time to time (maybe even for a few months at a time), but I'll do my best to keep it running. Naturally the more help that I get with info from the MVS experts, the better. Your help and that of others here is very much appreciated so far.

Okay, here's another update - revision 4 of the document can be found here:

http://www.mediafire.com/download.php?2jnlzifykt2

As for the document itself, it's coming along nicely - I am though still looking for RAM location info/confirmation of info already in the document for the following boards:

MV-1B
MV-1C
MV-6F

are there any other board revisions that I've missed? (for example, I'm aware of two revisions for the 2 slot which is significant enough to mean that the RAM chip locations differ - if there are any other boards affected this way please post here with the info).

Thanks

Double check your work on the MV6. I've never seen an MV6F - if it exists I would guess it would have surface mount chips on the top board like the MV4F does.

RJ

Is it not called the MV-6F then?

For most of my board naming I've been going by references this page:

http://hardmvs.com/html/PCBcompare.htm

Trouble is that I can't find a decent picture of the main board in a 6 slot in order to determine the RAM locations, and what I've put in the document has been obtained by from referencing posts here, some which have contradicted each other, hence any confusion on my MV-6F entry.

Someone here must have a 6 slot so they can confirm my findings .......... perhaps I should post a message in tech for any 6 slot owners?

There's only one 6-slot model and it's called MV6. The bottom board is practically identical to that of the MV4 (older 4-slot model), same components in almost the same locations. Coordinates are different though because of the different size.

http://img230.imageshack.us/img230/3870/mv6ok4.jpg

yellow = sound ram
blue = color ram
red = video ram
green = work ram
pink = backup ram

Fantastic, many thanks. Another doc revision on the way!

MKL said:

There's only one 6-slot model and it's called MV6. The bottom board is practically identical to that of the MV4 (older 4-slot model), same components in almost the same locations. Coordinates are different though because of the different size.

http://img230.imageshack.us/img230/3870/mv6ok4.jpg

yellow = sound ram
blue = color ram
red = video ram
green = work ram
pink = backup ram

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MKL - Can I be a pain and ask you to write down the actual locations please, it's just that I can't easily make out all the relevant letters on the left side of the board, partly due to the flash (I can make out the numbers though!).

Many thanks!

I don't have a 6-slot at the moment, only a few pics. This one and the other tell that the sound ram is at M1, the color ram at G4, H4, the video ram at L9, K9 and M-N11, the work ram at H9, J9, the backup ram at E9, F9.

Perfect, thanks, now updated the document to rev. 5 with your additional info:

http://www.mediafire.com/download.php?1dxeoclimly

MV1B:
http://img378.imageshack.us/img378/596/mv1bpt7.jpg

RAM1,2 = Work RAM
RAM3,4 = Backup RAM
RAM5,6 = Video RAM
RAM7 = Sound RAM

Other RAM is inside the big chip (for instance the color ram is in the upper left corner of the big chip).

Thank you kindly, now incorporated that into rev. 6 of the document:

http://www.mediafire.com/download.php?dmpjzxdr5xt

All we need now is RAM details for the MV-1C as well as any other intermediary revisions which change the locations of the RAMs.

I'm getting ready to replace the working SRAM SOIC chips on my MV4 and I'm curious if someone could help me determine if I got the right chips.

I grabbed (what were listed as) HM62256BLFP-12T chips that turned out to be HM65256BLFP-12T chips. Before I get a refund I wanted to know if the HM65256BLFP-12T chips would work, the stats look similar on the datasheets but they are 65256 and not 62256. Could someone look these over to see if I can still use the 65256 in place of the 62256?

If both are wrong that would be helpful to know as well, there are quite a few manufacturers making 62256 120NS chips.

Thanks!

Great doc! I can add that for a MV-4 the backup ram at D9 handles the first 2 bytes, and the ram at E9 the last 2 bytes of the read-value when you get a backup ram error. Could be helpful to identify a bad chip!