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NeXT DSP Memory Expansion Module
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pentium



Joined: 23 Jun 2006
Posts: 1146
Location: Kamloops, BC

PostPosted: Thu Oct 08, 2009 3:15 pm    Post subject: Reply with quote

Even if I could find some IIfx SIMMS I wouldn't dare ruin them.
Hold on for a second. *runs off*

Say, the SIMMS on this AST daughter card uses 64 pin SIMMS.
If anyone wants I guess I could at least quickly draw up some dimensions for the stick.
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-NeXT 68040 Cube with NS 3.3 and 64Mb ram
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Nitro
Site Admin


Joined: 22 Oct 2005
Posts: 421
Location: Littleton, Colorado USA

PostPosted: Thu Oct 08, 2009 4:24 pm    Post subject: Reply with quote

pentium wrote:
Even if I could find some IIfx SIMMS I wouldn't dare ruin them.
Hold on for a second. *runs off*

Say, the SIMMS on this AST daughter card uses 64 pin SIMMS.
If anyone wants I guess I could at least quickly draw up some dimensions for the stick.


Hereís some dimensional information for 64 pin SIMMs:

http://www.nextcomputers.org/NeXTfiles/Projects/DSP_Expansion_Ram/64_PIN_SIMM_632128w-z.pdf
http://www.nextcomputers.org/NeXTfiles/Projects/DSP_Expansion_Ram/AK63264AW.pdf

Iím not sure this applies but hereís the JEDEC standard:

http://www.nextcomputers.org/NeXTfiles/Projects/DSP_Expansion_Ram/JEDEC_64_Pin_SIMM.pdf

I have a 1mb 64 pin SIMM that I picked up cheap online that was made for an Apple LaserWriter. When plugged into a Turbo Color Slab the Slab wouldnít boot, but the SIMM fit. It could be used for a prototype if needed.

Edit:
Iím going to get some local bids on having this module designed, given the information that was sent to me and other irons in the fire. Weíll see what the cost will be for some prototype boards. If itís feasible from a cost standpoint Iíll pull the trigger and have some PC boards made. If that happens and the module actually works, all of the manufacturing info will be made available in the file archives here so that you can have your own boards made locally if you desire.
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pentium



Joined: 23 Jun 2006
Posts: 1146
Location: Kamloops, BC

PostPosted: Fri Oct 09, 2009 5:11 am    Post subject: Reply with quote

That's fantastic Nitro! Very Happy
Leave it to you to use your connections when ours fail.
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NeXTnewbe



Joined: 27 Oct 2006
Posts: 274
Location: UK

PostPosted: Fri Oct 16, 2009 12:48 am    Post subject: Reply with quote

I'm still trying to get a old MAC sim, so far I have check all the newer components, and the Austin Semiconductors are I think the best sutiable for the jobs as it seems that the design will not require any change


any news guys (Pentium, Nitro)
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Nitro
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Joined: 22 Oct 2005
Posts: 421
Location: Littleton, Colorado USA

PostPosted: Wed Oct 28, 2009 3:32 pm    Post subject: Reply with quote

I'm waiting on other people, so I don't have anything to report at this time.
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Zardoz



Joined: 28 Jun 2008
Posts: 61
Location: Berlin, Germany

PostPosted: Fri Jun 25, 2010 2:03 am    Post subject: dead or alive? Reply with quote

Is this project dead?
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pentium



Joined: 23 Jun 2006
Posts: 1146
Location: Kamloops, BC

PostPosted: Thu Jul 29, 2010 10:16 pm    Post subject: Reply with quote

I'm no longer able to produce the necessary PCBs that we can make the modules from unfortunately. I ahve done the best I could but all the necessary information is still available for someone else to carry the project on.
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balrog



Joined: 20 Jul 2010
Posts: 23

PostPosted: Sat Aug 07, 2010 2:04 pm    Post subject: Reply with quote

What about submitting the design to batchpcb.com (this is a spin-off of SparkFun) so if someone wants one they can easily get a PCB? Is a Gerber file available? Are there any blind or buried vias? I have a Cube and could use this module!
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sdinet



Joined: 25 Jun 2008
Posts: 184

PostPosted: Sun Aug 08, 2010 8:21 pm    Post subject: Reply with quote

I looking into this as well and making the PCBs will be a huge challenge as I believe they have multiple layers of traces. Our best bet would be to find an similar apple/mac simm that fits the pins, the remove the apple/mac chips from the simm and wire the proper chips to the pins (kind of like a breadboard).
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balrog



Joined: 20 Jul 2010
Posts: 23

PostPosted: Sun Aug 08, 2010 8:42 pm    Post subject: Reply with quote

sdinet wrote:
I looking into this as well and making the PCBs will be a huge challenge as I believe they have multiple layers of traces. Our best bet would be to find an similar apple/mac simm that fits the pins, the remove the apple/mac chips from the simm and wire the proper chips to the pins (kind of like a breadboard).


BatchPCB will make boards with up to four layers (two external and two internal). The prices for four-layer boards are higher, but still reasonable.
Basically, you send them a Gerber file (basically a file describing how the board should be made) and they'll produce the boards.

I've looked into PCB prototyping, and most other places charge a lot, especially for multilayer boards. Hopefully this would work...I'd love one of these modules!

Using "something like a breadboard" could cause timing issues. I don't know enough, but at high speeds, crosstalk and timing become a problem.
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pentium



Joined: 23 Jun 2006
Posts: 1146
Location: Kamloops, BC

PostPosted: Wed Aug 11, 2010 10:27 pm    Post subject: Reply with quote

From what I have looked up, the SIMMS use three layers. Back, middle, and front.
We can manufacture two layer SIMMS that are a lot easier to manufacture (and considering we have all the necessary documentation on the original SIMMS, we know what each trace and component does). The problem however is that dropping to two layers requires the trace layout to be redone from scratch as well as the SIMM might become larger. We can built it outwards ot the sides without much trouble but we can't build up ot else we won't be able to fit them in our systems.
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balrog



Joined: 20 Jul 2010
Posts: 23

PostPosted: Wed Aug 11, 2010 10:42 pm    Post subject: Reply with quote

pentium wrote:
From what I have looked up, the SIMMS use three layers. Back, middle, and front.

A quick overview of the PDF indicates that there are four layers: two outer layers, a power plane, and a ground plane. This is a quite common practice in board design.

pentium wrote:
We can manufacture two layer SIMMS that are a lot easier to manufacture (and considering we have all the necessary documentation on the original SIMMS, we know what each trace and component does). The problem however is that dropping to two layers requires the trace layout to be redone from scratch as well as the SIMM might become larger. We can built it outwards ot the sides without much trouble but we can't build up ot else we won't be able to fit them in our systems.


Another thing to worry about is timing issues. Any time the position of traces is changed, timing might be messed up and it may just stop working properly. Here is an example of this (and note that SRAM is usually accessed faster than 150ns or slower DRAM).

How do you intend to manufacture the boards? I figured that using a service, such as BatchPCB, would be most feasible -- although not exactly inexpensive: they charge $10 + $8 per square inch for 4 layer designs or $2.50 for 2 layer designs. There are other services, but so far I couldn't find one as inexpensive for small production runs (1 or 2 boards).

The actual work would be to transfer the design from the PDF to software such as Eagle or other PCB-design software and get the dimensions right. Afterwards, a Gerber file can be exported; this file format is what BatchPCB and others accept. Assembling isn't a big deal for anyone with a decent soldering station, though I'm quite sure there will be a market for pre-assembled SIMMs.
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NeXTnewbe



Joined: 27 Oct 2006
Posts: 274
Location: UK

PostPosted: Thu Aug 12, 2010 3:00 am    Post subject: Reply with quote

I would like to have one of this boards too, but I remeber that the professro who give us the information, advice on use the memory replacements as the originally used are not in production anymore and if found they can present problems (cant remeber why), he advice to redisign the board to fit more modern SIMMs

but I would like to help anyway Smile
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balrog



Joined: 20 Jul 2010
Posts: 23

PostPosted: Thu Aug 12, 2010 6:56 am    Post subject: Reply with quote

NeXTnewbe wrote:
I would like to have one of this boards too, but I remeber that the professro who give us the information, advice on use the memory replacements as the originally used are not in production anymore and if found they can present problems (cant remeber why), he advice to redisign the board to fit more modern SIMMs


My understanding was that the company that made the ICs doesn't make them anymore, and used old-stock may be defective. Fortunately, a company was found that makes functionally-identical parts.

In my opinion, re-engineering should be avoided if at all possible.
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NeXTnewbe



Joined: 27 Oct 2006
Posts: 274
Location: UK

PostPosted: Thu Aug 12, 2010 9:52 am    Post subject: Reply with quote

I didn't know that, Thanks

well I'm in Smile
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