32MB for your Amiga for 22$ ?

[Oli_hd]

One of the reasons why it is not possible to use just any type of RAM in a 3000 is because of the memory refresh system impersonated by RAMSEY

Ermm, 30 pin and 72 pin SIMMs would run just fime from the Ramsey timing.. ok you couldnt stick SD-Ram in but a 72 pin adaptor would be much easier to do. (And has been done before, including free designs available from Aminet today)

I found this chip on Digikey which can be purchased by the unit for 11$ each: http://download.micron.com/pdf/datasheets/psram/BurstCellularRAM1.5_128Mb.pdf    This chip has 16 data lines and contains 128Mb of data therefore two of them fullfills the 32bit data bus requirement for 68030, 040 and 060 processors and give you 32MBytes for 22$. I

Ermm its a 16 bit chip that gives you eight megabyte of memory, sticking two side by side (Connected to the same address pins) would give you 16, an address decoder would be needed for 32. (and four memory chips)

I can't believe you are trying to charge people $22.00 for only 32 MB of ram. That smells outrageously expensive.      Well, I wish you real good luck getting the corner PC store's DDR SDRAM to work on a 68k based Amiga...

I think he was commenting on your use of "outrageously expensive" when talking about the ZIP ram, it isnt expensive (Your not ment to use it for adding loads of ram, at 1meg its cheap) its just there are cheaper options, you give the BGA memory chip, he gives you PC DDR Ram.

How many address lines exactly are there on the Z3 bus? I think that's 32 and therefore your fast RAM limit is more like 4GB (but that would probably be 2GB cuz you always have to have the custom chips and the chip RAM somewhere).

Actually 31, it doesnt support 8 bit reads, it reads 16bit at a time minimum, regardless wether or not only 8 bits are in use. but thats a nothing reply, yes the CPU is 32 bit and it can address 4GB total.

Take a look here:  http://www.thule.no/haynie/zorroiii/docs/zorro3.pdf    I bet you could avoid the autoconfig stuff and put the memory at a fixed address (or have a choice of addresses by jumper setting). Then run a utility in startup-sequence to add the memory.

Actually that card uses ZIP ram too, although adding 72 pin SIMM slots would be a piece of cake. Its a good design and if you wanted to make a memory card that is the design you should use. Upping the maximum RAM is just a matter of adding another 74257 (or 258) to get the extra address lines as the Miggy will detect how much ram is on the card.

Its also a lot easier than your BGA memory chip which would still require logic chips as CRE and ADV would have to be generated.

If you're planning to build a Zorro RAM expansion, why not build it to accept DDR/SDR? Is that possible?

It is, Xilinx have a design you can download, as do opencores I think.
All someone has to do is try... oh but they will have to add autoconfig and make sure the output bus is 68K compatiable. Also SD and DDR ram are clocked memory, the Zorro bus is asyncronous memory, its not great to mix the two busses... that said you look at 90% of Z3 boards and they are syncronous.
Get designing people.

eslapion: To sum up, designing a 72pin SIMM board would be much easier for a hobbiest to do than to start playing around with high density BGA chips.
32Meg 72 pin Simms are still available new, cheap, from most PC suppliers. Eclipse computers here in the UK sell them for £5.82 each. Make a Fastlane type board with 16 72 pin slots and you get half a gig for less than £100

[Oli_hd]

yup, get a list of people who would be interested, hand it to Jens and see.
I dont know what Jens is working on now, it may be an ideal time to ask.

[Oli_hd]

Any idea what a DKB 3128 goes for these days if you can find one?

About $150 USD, more for a Fastlane (Specially if the guy words it like it "may" have the 256Meg upgrade)
Aim at £100 and it would be Jens most expensive card I think, so thats a good target.
512Meg Z3 memory card please.

[Oli_hd]

Basically, wanting a 128MB RAM card on a Zorro II card for the A2000 is just an impossible dream, right?

Correct, no way around the 8meg Zorro limit.
However I assume as your using an A2000 over an A3000 you have a CPU upgrade in the A2K, that could take a suitable card.
For example my A2630 has the full 32bit address and data lines brought out to two connectors (Which is why there is the 2632, a memory card for the A2630 that plugs into said plugs)
Also a new A2000 CPU card could be made with as much ram (less than 4gig - 16meg) as wanted.

[Oli_hd]

Why not simply use one of those boards on a carrier designed to fit the Zorro slot?

Do you like the look of the XSurf?
carrier boards suck eggs.

[Oli_hd]

Re: ZIP to SIMM Adaptor
I suspected something like that. Would you have a few links to these free designs?

http://aminet.net/hard/hack/PS2_adapter.lha is the A3000 adaptor with image of the PCB you need to make.
Amifast card
was a card made by Provtech but chances are you will see more of Kato's simmfonie card.

Re: Z3 memory card:
What card exactly are you referring to?

The Commodore Bigram, it was made as a Z3 reference design back when the A3000 was launched to show CAT's developers how to design Z3 cards. The design was given away free and is still available from the Dave Haynie archive
More information on the card, including a picture, is available at amiga-hardware.com

Now thats the kind of technical hurdle I wanted people to tell me about. What exactly are CRE and ADV ?

They are specific to that chip I think, unlike normal ram you have to tell this when your not using it or if your running a burst cycle, these extra signals combined with the normal signals are used for that. Details are in the PDF of that memory chip you were talking about.
Normal Dram (And SDRam) havce RAS and CAS and thats it (SDRam add chip select, or BE, but they are just address lines)

Electrically, static memory chips seemed much easier to deal with than DRAM. However, soldering VFBGA (that's VERY FINE ball grid array...) chips would certainly be a true pain in the neck...

Well SRAM is, this ram you linked to isnt. SRAM is treated just like a ROM and is dead easy, everything is sorted inside the chip. Down side is SRAM is expensive and the memory you linked to would need extra chips to control it, just like DRAM does (Although not the same chip as the lines do different things)
DRAM is simple, you just have to split the address bus and load it into the ram half at a time (using RAS and CAS to tell the RAM what half is on the address bus at that time) and refresh the ram every so often so the contents are not lost.
Have a look at some of the Zorro 2 dram cards on amiga.resource.cx, there are some simple designs.
Zorro 3 just adds address and data latches and adds more memory.

I don't give a rodent's rump what it looks like, so long as it works.

:-?  I want the Delfina lite, not because its the best card but because its sexy.  :-D

[Oli_hd]

While the slot is 64 bit the DIMM memory modules are often made up of 8 or 16 bit IC's which are controlled by the DQMB lines on the SD-Ram connector.

There are 8 DQMB lines, enough for 8bit control of the 64bit bus, technically you could interface an 8bit CPU to the SD-Ram, the down side is like I said, some are chained as 16bit, some I think even 32 but Im 90% sure there are no 64bit only DIMM's.

Some good reading on SD-Ram DIMM layouts is available from this document:
PC133 SDRAM Registered DIMM Design Specification Revision 1.1

And for a more techincal doc on how SD-Ram works you need to read this:
PC SDRAM Specification Revision 1.7

The only reason why some MINIMAL logic would be required with PSRAM, as far as I know, is the autoconfig procedure.

Your memory speed would such, you will need to implement a burst system.. which is Z3 specific (Well its based on the 030 bus burst system but you know...) and without that its one read or write per bus cycle vs four using burst.

Also Z3 has a multiplexed bus, the data and address busses are the same thing, it just has an address phase and data phase, your going to need the full array of bus buffers and latches to decode that.

Its still going to be a big job... your best bet would be to get a nice big CPLD or FPGA and connect the Zorro bus to one end and the SD-Ram slot to the other then work everything out in software.

Final edit: As a little example Eclipse computers (A cheap ass UK computer company) is selling a 512Meg SD-Ram DIMM for £30 and they list it as a 16 chip module with each chip having 32meg and an 8 bit bus. Which technically gives a 128bit bus, so every two chips must be coupled to the same DQMB line, giving a 16bit CPU bus, taa dahh.

So who's making a Z2 version? (I joke, although you could have a rather nifty 8meg SD-Ram upgrade card working on an A2000)