MrFahrenheit
Well-known member
Are you still making and selling these? I’d love to have higher capacity than some 1MB that I have.
How many working IIfx are there? Very good question! Also, working when sold or working after fixing? I have two IIfx machines myself, and I’ve seen at least 5 others on eBay just in the past 6 months. So on eBay alone in the last 6 months at least 7 (including my 2).32MB is plenty but if you are going to make SIMMs you might as well make the maxed out ones (you don't need both banks filled anyway).
Any clue how many working IIfxs are out there in the world? 1000's, 100's?
How closely do your PCB's match the "real deal" in thickness? Is there a difference between two layer and four layer boards in thickness? Six layer boards? Curious if the SE/30 RAM PCB thickness may be rearing its ugly head for IIfx SIMMs as well? Might tinning your contacts make for better physical fit in the slot? Un-plated edge card teeth might work to your advantage there.I made myself some 2-layer SIMMs for the IIfx based on the 4-layer design joe used.
Couldn‘t get them to work yet but I also went for the cheapest non-gold plated PCB option so I suspect they do make very bad contact.
Stopped to care after a few tries because 32MB is actually enough for my IIfx.
Gotta dig those out and see if I can actually get them to work.
For obvious reasons, everyone's been looking for RAM to populate 16MB boards. Are RAM ICs more available that might make up 4MB-8MB SIMMs?In the end the hard part won’t be making the PCBs but sourcing the dual ported RAM chips you need in large enough quantities.
IIfx SIMMs are also .050" thick, and so will have the same issues seen elsewhere if one settles fro 1.2mm thick boards.How closely do your PCB's match the "real deal" in thickness? Is there a difference between two layer and four layer boards in thickness? Six layer boards? Curious if the SE/30 RAM PCB thickness may be rearing its ugly head for IIfx SIMMs as well?
PC substrate: 1,27 ± 0,1 mm
I'll most likely limit sales to 4x16MB per individual so everyone can at least get a bunch of RAM. If there are leftovers, I'll do a round two.Would love to be the first to purchase a 128MB set once you have them ready. I have a bit of extra cash right now.
Just wondering what kind of anticipated cost you'd be placing on 4x16MB modules. Not going to hold you to it, just an estimate. I'd very much be interested in 4x16MB for my IIfx pair. Even if I could just upgrade one for now, that would be great!Hi @dougg3,
Thanks so much for designing these. [8D]
The only place that would do 1.27mm boards was allpcb, and it took a bunch of emails, a special setup, and it more than doubled the price of the PCB.
I'll most likely limit sales to 4x16MB per individual so everyone can at least get a bunch of RAM. If there are leftovers, I'll do a round two.
Perhaps make this optional, and provide a kit of cut strips upon request for the user to apply as needed, since the tolerance of SIMM slots seems to vary (some work fine with 1.2mm SIMMs, whereas others seem to require 1.27mm exactly).Here's a tape that is 1/4" wide, 3 mil thick and since it is from 3M it is probably actually very close to the specification. Adding this to clean PCBs would give you 1.276mm thickness. 3M Polyimide Film Electrical Tape 1205