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AuthorTopic: 32MB for your Amiga for 22$ ?  (Read 1761 times)

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Offline Oli_hd

Re: 32MB for your Amiga for 22$ ?
« Reply #15 on: March 06, 2007, 04:02:56 PM »
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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.
 

Offline Oli_hd

Re: 32MB for your Amiga for 22$ ?
« Reply #16 on: March 06, 2007, 04:07:04 PM »
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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.
 

Offline Zac67

Re: 32MB for your Amiga for 22$ ?
« Reply #17 on: March 06, 2007, 06:59:20 PM »
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DamageX wrote:

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.

Quoting The Master and writing this in one and the same post - you must be out of your mind...  :roll:
The Autoconfig logic is very easy to do.

@all
Actually I doubt if there's really a large demand for Z3 RAM boards: they're slower than onboard RAM (which isn't fast either) and paired with a CPU board will be a real pain. A far superior solution is to add the RAM on an accelerator board - which is why nearly all of them come (came) with RAM slots.
 

  • Guest
Re: 32MB for your Amiga for 22$ ?
« Reply #18 on: March 07, 2007, 04:56:39 AM »
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Oli_hd wrote:
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 suspected something like that. Would you have a few links to these free designs?

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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.


What card exactly are you referring to?

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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.


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

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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.


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...
 

Offline JimS

Re: 32MB for your Amiga for 22$ ?
« Reply #19 on: March 07, 2007, 02:31:24 PM »
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Oli_hd wrote:
Do you like the look of the XSurf?
carrier boards suck eggs.


Actually, I don't give a rodent's rump what it looks like, so long as it works. ;-) My thinking was this was a personal hack, not a commercial product. So it would be easier to produce a carrier board that fit the Zorro slot and could be hand soldered, rather than try to deal with those SMT chips.

-Jim
Obsolescence is futile. You will be emulated. - Amigus of Borg
 

  • Guest
Re: 32MB for your Amiga for 22$ ?
« Reply #20 on: March 07, 2007, 04:55:45 PM »
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JimS wrote:
Actually, I don't give a rodent's rump what it looks like, so long as it works. ;-) My thinking was this was a personal hack, not a commercial product. So it would be easier to produce a carrier board that fit the Zorro slot and could be hand soldered, rather than try to deal with those SMT chips.

-Jim


Well, it "could" have become a commercial product...
 

Offline JimS

Re: 32MB for your Amiga for 22$ ?
« Reply #21 on: March 07, 2007, 07:55:57 PM »
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eslapion wrote:
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Well, it "could" have become a commercial product...


It still could, if someone thinks there's a big enough market to make it worthwhile.
Obsolescence is futile. You will be emulated. - Amigus of Borg
 

Offline DamageX

Re: 32MB for your Amiga for 22$ ?
« Reply #22 on: March 07, 2007, 08:29:48 PM »
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Quoting The Master and writing this in one and the same post - you must be out of your mind...  
The Autoconfig logic is very easy to do.

LOL, well if we're already considering pseudo-SRAM instead of SIMMs or DIMMs then I say leave no corner uncut.
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Z3 RAM boards: they're slower than onboard RAM

If I'm not mistaken (no, I did not read through the whole Z3 spec) a Z3 board COULD be as fast or faster when taking advantage of faster memory. A3k/A4k onboard memory is 80 or 100ns right?
 

Offline Zac67

Re: 32MB for your Amiga for 22$ ?
« Reply #23 on: March 07, 2007, 08:54:46 PM »
Well, in theory a Z3 card could be faster than A3k/4k onboard RAM - but not with existing chipsets. A3k/4k can't drive the bus as fast as they can access Ramsey mem.

Onboard RAM must be 80ns or faster, yes.
 

Offline KThunder

Re: 32MB for your Amiga for 22$ ?
« Reply #24 on: March 07, 2007, 08:59:41 PM »
z3 access is multiplexed address/data cycles. that puts a layer between the cpu and bus controlled by the chipset. dma burst modes are similar but different than 030 and quite a bit different than 040 burst.

i dont think it could be as fast.

a memory card that clipped on top of surface mount 030 or under pga 030 or 040 would be better. there is better info on the interface and it would concevably be usable on accel boards as well.
Oh yeah?!?
Well your stupid bit is set,
and its read only!
(my best geek putdown)
 

  • Guest
Re: 32MB for your Amiga for 22$ ?
« Reply #25 on: March 08, 2007, 12:20:45 AM »
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KThunder wrote:
z3 access is multiplexed address/data cycles. that puts a layer between the cpu and bus controlled by the chipset. dma burst modes are similar but different than 030 and quite a bit different than 040 burst.

i dont think it could be as fast.

a memory card that clipped on top of surface mount 030 or under pga 030 or 040 would be better. there is better info on the interface and it would concevably be usable on accel boards as well.


Well, considering we're dealing with ultra small chips, it could be possible to make some card that gets sandwiched between a 680(3 or 4 or 6)0 and its socket.
 

Offline Oli_hd

Re: 32MB for your Amiga for 22$ ?
« Reply #26 on: March 08, 2007, 09:42:03 AM »
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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.

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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

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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)

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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.

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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
 

Offline mrmkl

Re: 32MB for your Amiga for 22$ ?
« Reply #27 on: March 08, 2007, 02:19:51 PM »
Eslapion about DDR:
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...Amiga it would probably cost no less than 100'000$ to develop. When you can spread this cost across millions of units you know will sell, that's not a problem. The Amiga community doesn't have such a large user base to justify that.

$100000 for development sounds a bit pricey, i don't buy that. Maybe some $1000s is more realistic. How about SDR-SDRAM, which is a bit more simple to interface. And a bit more expensive, unless bought second hand.
It wouldn't need many parts: One PLD, one (or more) SDRAM-socket, a printed circuit board and some capacitors, resistors, and a voltage regulator or two.

 

  • Guest
Re: 32MB for your Amiga for 22$ ?
« Reply #28 on: March 08, 2007, 07:35:01 PM »
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mrmkl wrote:
$100000 for development sounds a bit pricey, i don't buy that. Maybe some $1000s is more realistic. How about SDR-SDRAM, which is a bit more simple to interface. And a bit more expensive, unless bought second hand.
It wouldn't need many parts: One PLD, one (or more) SDRAM-socket, a printed circuit board and some capacitors, resistors, and a voltage regulator or two.


The problem with both SDR SDRAM and DDR SDRAM DIMMs is that they were designed to be accessed with 64 bit data busses.

Now, that's fine with processors from the original Pentium I all the way up to the fastest core 2 duo which have 64 data lines (in Pentium I systems, 10 years ago, 32 bit 72 pin SIMMs had to be installed in pairs). However, it is a major problem with 680X0 systems which cannot access more than 32 data lines at a time.

Here is the kind of problem that it causes. Let's say you want to write into the lower half one of the 64bit cells of a DIMM with a 68040. You first have to read the content of the cell into a buffer so you know what was first in there. Then replace the content of the lower portion of the buffer with what the processor wanted to write in there, then write this back to the cell.

As you can see, this is quite complicated.

One of the reasons I originally suggested PSRAM, is that, by pairing 2 of these 16 bit chips together, you get exactly 32 data lines. So theoretically, you could attach chips like that without ANY logic devices at all directly to the bus of a 68030, 68040, 68060 or even an intel 486 processor.

No refresh, no multiplexing needed and no logic to compensate for inadequate bus width. Perhaps a few simple 74XX chips for address decoding.

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

Offline Zac67

Re: 32MB for your Amiga for 22$ ?
« Reply #29 on: March 08, 2007, 07:54:47 PM »
I've also pondered on the 'SDRAM DIMMs are 64 bit wide' problem a bit.
Given the low price of the RAM, you can just use one half of it and forget about the rest (either double data or ignore it altogether). If you want large amounts of RAM, it's the easiest and cheapest solution - you could even use slightly defective modules. ;-)
Aiming at the 16 to 128 MB size range, it's surely easier and cheaper to use old PS/2s, they're free.