GVP Compatiable 4MB 64-Pin SIMM Design

I've been an Amiga user, and overall Commodore user, since the 80's and this is my first post to this board so I hope everybody finds it helpful.

Had my Amiga 500 with GVP A530 accelerator out lately and wanted to upgrade to a full 8M of RAM. After lots of searching on this board, and others, I found that getting the GVP 64-pin SIMMs these days was fairly difficult. And much like others I found GVP-M (http://www.gvp-m.com/) less than helpful. I found this work (http://aminet.net/package/docs/hard/gvpsim64) from Pascal Janin from the 90s which I'm sure a lot of you know. After reading that I thought to myself "I'm a EE with my own home lab, I can make these". So using Janin's work as a starting point and also using the 1M SIMM that originally came with my A530 I set off to work building my own.

Bare circuits boards:



Stuffed circuit boards:


Boards mounted in A530:


Even though I triple and quadruple checked everything I was fairly amped up when I applied power. If something went wrong its not like I can just go and buy another A530 at the store. Not only did it power on but booted in half the time with more fast RAM to use. Ran a battery of tests on them (checkerboard, walking ones, walking zeros, etc.) and everything passed. Ran some graphic animation programs and VR studio stuff to really exercise them with no issues.

I got the memory chips from Syracuse Semiconductors (http://syracusesemiconductors.com/) via their eBay page (http://www.ebay.com/itm/MT4C4001JDJ-...MAAOxy3zNSkmC4) for $2.50 a piece plus shipping. They are pulls but came in good shape and appear to be fully operational. The boards were ordered from a PCB manufacture that I use for production and prototype boards. Unfortunately those are the expensive pieces when orders in low quantity. I ordered 5 at $14.64 a piece plus shipping.

The attached ZIP file contains the schematic, gerbers, and a README with specifications and information. The project was designed in Protel 99SE. I freely release this information out into the wild in the hopes that others will find it helpful. Board assembly by hand wasn't bad. Normally, SOJ packages are fairly straight-forward as far as SMT parts go for hand placement, but since they are packed together closely on the board that added a little more difficulty.

I took one design liberty. The original SIMMs did not have any bypass/coupling capacitors. This was common for the time, not just with GVP, to save every penny. I added a 1/16" to the board height and placed pads for 0402 bypass capacitors. I rather have them and not need them, then need them and not have them. I've been testing without them and all is working well but their there for piece of mind.

[hese]

Good job, well done

[Magic]

Awesome!

Thank you

[dalek]

Wow - thank you!

[grelbfarlk]

In case someone finds this useful, here's a 16MB GVP SIMM PCB. The caps are 1206 size 0.22uf.

[KronusOfChaos]

That is awesome.

[idrougge]

You've done a great deal of Amiga users a big service, sir.

[Locutus]

How i wish now i hadn't sold my GVP530 :'-(

[demolition]

This is similar to this one right?
http://www.amibay.com/showthread.php...-with-warranty

But great to have a DIY project as well.

[dalek]

So I went to DirtyPCBs and got this error:

"No board outline (.GML/.GKO/.GBR) file found."

Does anyone know if I can generate that somehow or if not could djbcoffee please attach it?

Really keen to get some made up and max out my 030 combo

Thanks everybody. I'm glad this work is helping.

@demolition - Yep, I did see tbtorro's work while I was initialing researching. Alas, the A530 only uses 1M and 4M SIMMs so I had to roll my own.

@dalek - I've only run into a few board houses that required a separate board outline during my career so I don't think much about it much. Thanks for bringing this issue to our attention. I cooked up a new batch of gerber files that now have a separate board outline file and attached them in the ZIP file with the name "GVP Compatible 4MB 64-Pin SIMM Rev A - Sep Outline.zip" for "Separate Outline". Protel 99SE uses mechanical layers for board outlines so in the ZIP you'll see a new gerber file with the file extension .GM4 for gerber mechanical layer 4 (which is where the outline is in the project). You can rename the file extension to whatever your board house needs to identify it as a board outline layer.

Speaking of 1M SIMMs. If anybody is interested this is the same board you would use for a 1M SIMM module. The 256K by 4Mbit chips used on the 1M SIMM module and the 1M by 4Mbit chips used on the 4M SIMM module both come in the same 20/26 SOJ package. The only difference between them is that pin 5 (address 9) is not used on the 256K by 4Mbit chip. I traced out the GVP 1M SIMM module I have here and A9 is indeed routed to pin 5 of each chip on the board. Since the pin is not internally connected no harm done. GVP Could use the same board for both module sizes. The chip package for the DRAMs on the 16M SIMM is a 24/26 SOJ, as shown in grelbfarlk's pictures above, so a separate board is needed for them.

[dalek]

Thanks for that - I removed the .pdf and README.txt, renamed the GM4 to GML, re-zipped and it passed the checks

[_tweak]

Note - instead of buying the pulled dram, if you have access to a heat-gun, it might be much cheaper to buy the right 72-pin ram, and desolder the ram from there and solder it to these boards. Also, supplies of 72 pin ram isn't exactly scarce anyway :-)

There are probably (I guess?) a bunch of compatible RAM, I will try to make a list. For those with the will to trade on alibaba, this might be the correct dram; https://www.alibaba.com/product-deta...838.0.0.ZvdQEE (alas who really know..)

Edit (1): I compiled a list of might-be-compatible 1Mx4bits RAM, however im not really that much of an expert, so if "someone" would revise the list :-)

Hitachi: HM514400
Samsung: KM44C1000
Mitsubishi: M5M44400
NEC: 424400
Toshiba: TC514400
TI: TMS44400
MicronTech: MT4C4001
Hyundai: HY514400

Edit (2): I went through all the datasheets of the above, and I came up with these model-numbers (and their speed). One has to really double check the datasheets before bying in bulk :-) I do not know what the overall maximum access time are for the RAM, however the one djbcoffee linked to is 60ns, 16ms refresh time, 300 mil SOJ.

Samsun KM44C1000DJ-5 (50ns)
Samsun KM44C1000DJ-6 (60ns)
Mitsubishi M5M44400CJ-5 (50ns)
Mitsubishi M5M44400CJ-6 (60ns)
NEC PD424400LA-60 (60ns)
Toshiba TC514400ASJ-60 (60ns)
TI TMS44400-60 DJ (60ns)
MicronTech MT4C4001JDJ-6 (60ns)
Hitachi HM514400ASLS-6 (60ns) // probably one of these triplets
Hitachi HM514400ALS-6 (60ns) // is actually right
Hitachi HM514400AS-6 (60ns) // so beware

Edit (3): Removed >60ns chips.

[_tweak]

@djbcoffee: Just asking in theory; with a bit of rewiring, could this be turned into a project using a more available RAM-package, like the a 1Mx8-Bit SOJ ? (large footprint, but its still solderable by solder-noobs) - or are there a specific hardware-cause that makes anything less than, say 4 chips (e.i for a 4x8bit = 32bit output, instead of 8x4bit) inconvenient ? Could it be a space issue?

Unfortunately ram now a days comes in TSOP packages, its was hard finding something even remotely available that wasn't "pulled" or "used, but as new", as an alternative (if it ever came to that).

Thanks for all your work - I have ordered a batch with DirtyPCB - and some DRAM

Originally Posted by _tweak

@djbcoffee: Just asking in theory; with a bit of rewiring, could this be turned into a project using a more available RAM-package, like the a 1Mx8-Bit SOJ ? (large footprint, but its still solderable by solder-noobs) - or are there a specific hardware-cause that makes anything less than, say 4 chips (e.i for a 4x8bit = 32bit output, instead of 8x4bit) inconvenient ? Could it be a space issue?

Unfortunately ram now a days comes in TSOP packages, its was hard finding something even remotely available that wasn't "pulled" or "used, but as new", as an alternative (if it ever came to that).

Thanks for all your work - I have ordered a batch with DirtyPCB - and some DRAM

@_tweak: Yes, something could be done with modern memory but it would take a bit of work. You could design a SIMM that uses modern SDRAM or SRAM and design an interface circuit that makes it look like eight 2nd generation DRAMs to any hardware connected to the SIMM. If there were enough demand for these SIMMs then it might be a worthwhile venture. But, then again, if there were enough demand we could source the original DRAMs from one of the warehouses I found that are stocking these original DRAMs. There are a few overseas and at least one I found close to here in California that have leftover stock from the final runs of these 2nd gen DRAM chips in the mid to later-half of the 90s.

[Codetsu]

Wow thanks even my GVP boards are full
7o7

[Pat the Cat]

Respect shown for a very useful project.

[thebajaguy]

Many thanks for doing the reverse engineering work on these. I will be trying them out in the upcoming months, and put my hot air station to work. I happen to have a batch of new DRAM on hand that can go on the 16M modules, so I will be making at least a few.

Rob @ GVP Tech Support '89-'93

Hello,

great job

do or would someone plan a PCB batch based on "pre-orders"?

I have a GVP combo and would like to get 3x 4Mo,
I can try the soldering but I am probably not skilled to deal with PCB ordering.

Originally Posted by Astro68k

Hello,

great job

do or would someone plan a PCB batch based on "pre-orders"?

I have a GVP combo and would like to get 3x 4Mo,
I can try the soldering but I am probably not skilled to deal with PCB ordering.

If there is enough interest then a small run of bare PCBs could be ordered. To get respectable pricing batches of 100 PCB pieces minimum would be needed. The PCB house I ordered them from is quoting $1.84USD per PCB at 100 piece pricing. Shipping would need to be added which would probably add maybe $0.30USD to $0.40USD per board.