IIfx 64 pin SIMMs: are you interested

[hellslinger]

I found some lots of chips on ebay used on 4MB 64 pin SIMMs, M5M44100BJ. I'm going to do a circuit board layout and will have a few SIMMs made at a local PCB shop.

It would offset the cost to have a bunch made, and I'd sell them at cost. Would anyone be interested?

 

[Byrd]

Yes - at least two sets here (of 4); what sort of price do you think they'd set you back, and any chance you could do 16MB SIMMs (then I'd be asking for more sets)

 

[hellslinger]

If I can find out what the chips that go on a 16MB module are, I will layout for that. Can you send me a picture or model number?

 

[Unknown_K]

Somebody here has done the work for making 16MB IIfx SIMMs. You might want to research and contact them.

 

[ArmorAlley]

I'd be very much interested in sets of 4 16MB SIMMs for the IIfx. I'd be happy to pay $50 for a set of 4x 16MB SIMMs. I'd want 2 sets too.

 

[bigmessowires]

See https://mac68k.info/forums/thread.jspa?threadID=363&start=15&tstart=0

 

[Byrd]

That would be member trag to contact on the forums re: additional info and chips for 16MB.

 

[zackl]

I'm in for the 16's !

 

[dougg3]

bigmessowires pointed to a link on mac68k.info in a post above. Just wanted to explain a bit -- I actually designed my own 16 MB IIfx RAM SIMM earlier this year. I only made 9 SIMMs--just enough to give my IIfx 128 MB with a spare. The CAD files (Eagle and Gerbers) are available at that link if anyone's interested. Some of trag's info posted here on 68kmla was useful for finding an affordable way to obtain the chips. The design is my own 4-layer design that I made for fun--not based on trag's at all.

I'm not planning on selling any, but another guy in the linked thread bought a bunch of chips and had a bunch of PCBs made. I think he's planning on making a bunch of them. It might be worth checking with him. At the very least, my 16 MB SIMM design is already out there if it helps speed things up

 

[hellslinger]

dougg3,

This is great, if your SIMMs work then there's no point in me iterating on an untested layout. Thanks for posting!

There is a local place that will build boards kitted, so I can send them a big stack of those samsung chips with the gerbers and have a bunch made. I'll get a quote this week and let everyone know. 

I would not expect to get an entire set ( of these SIMMs for less than $50. If dougg3 got them done flowing solder himself for 12 dollars a piece, it's impossible that a manufactured set will be close to that price.

 

[dougg3]

Excellent! The SIMM design has only been tested on my IIfx...but it works for me! The only real question I had was that the RAM chips have two pairs of VCC/GND pins, and I only put 0.1 uF decoupling caps on one of the pairs. Seemed to work OK, and also seemed to be what the DEC SIMMs I stole them from did. Not totally sure though...

Yeah, deciding on pricing is interesting. If you can get the quantity high enough, maybe it would be possible to lower the price by having a bunch made at once. I actually built 9 SIMMs for less than $10 each, but that didn't include shipping costs or any of my assembly labor. In really low quantities it's just not economical to have a board house do assembly for you. I'll be interested in hearing what kind of a quote you get!

FWIW, I don't know if my layout is compatible with the chips for smaller SIMMs. Only tested with the 16 MB variety, dunno if the RAM chip pinout is different between them.

 

[hellslinger]

I'll be using the chips you used: I don't think anyone is interested in anything less than 16 MB modules, and the chips for 4MB are the same price, so there's no reason to go with the smaller capacity SIMM. The only reason I first thought of 4MB modules was that they were the only chips I was able to confirm were actually put on IIfx SIMMs (I just didn't know what to look for and couldn't find pictures until you posted the designs). Finding FPM chips is hard to begin with, and going through datasheets on some unknowns to verify timing is probably impossible.

I believe the strategy for getting the best price will be asking how many SIMMs they can make from a single PCB sheet, and order that many. The less time my project is in their machines the cheaper -- it isn't necessarily a matter of complexity or part volume.

The shop I'm getting a quote from does very elaborate and high density boards, so a few J-lead chips on 4 layer is a cakewalk. I'm sending the gerbers tonight and should be able to get a quote within the week.

Thanks again for posting the design files. I'm consistently surprised and impressed by this community.

 

[Hotdog Zanzibar]

Did someone say 16s??  :drool:

 

[zackl]

Awesome! Maybe set up a quick gofundme.com or indiegogo once u get the quote back to make the process simple for u

 

[dougg3]

Just want to repeat in case you missed it at the other thread: the SIMMs need to be 1.2mm thick, not the typical 1.6mm. 1.6 is too thick and won't fit in the socket.

 

[hellslinger]

Sadly, the production costs for 64 assembled SIMMs would be nearly $35 per SIMM. I've asked the manufacturer to give me a quote for non-assembled SIMMs, which should be ~1/3 the price.

 

[moving2]

I am definitely interested in these. 

 

[moving2]

...just bumping to see if there is an update on this. 

 

[hellslinger]

I have yet to find a quote that would put the price close to what people would be willing to pay. I'm considering starting a kickstarter or indygogo to fund a large volume. I'm in grad school and the semester just started, so I haven't had a lot of time to pursue it, but I haven't forgotten.