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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: on February 20, 2007, 03:15:07 AM
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Here is a burning questions for you guys. Possibly a complex one.
I thought after all these years the cost of Amiga 3000 RAM would have gone down. It seems I was quite wrong.
ZIP chips are extremely difficult to find. However, I have ton of old SIMMS which carry exactly the right type of chips the 3000 used but in SOJ format instead of the needed ZIP package.
I have found a company which makes SOJ to ZIP adapters that perfectly matches the required pinout for the 3000. See : http://www.accutekmicro.com/product_detail.cfm?Product=DRAM%20ZIP%20Adapters
However, they cost 4$ each. That's 128$ for 16Mbytes and add to that all the works or resoldering the chips.
Does anyone have a better solution?
Thank you all!
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Yes, buy a decent accelerator (http://cgi.ebay.com/Amiga-4000-Warp-Engine-Accelerator-NewTek-Video-Toaster_W0QQitemZ320084474465QQihZ011QQcategoryZ4598QQssPageNameZWDVWQQrdZ1QQcmdZViewItem) for your A3000 and forget about the on board ram :)
The zip rams on an A3000 mobo is a tight fit. I'm not sure these adaptors with chips on them would fit in there. Not worth the trouble me thinks.
PS : the seller does not have a very good reputation though, so be warned. You can read more about her here (http://www.amiga.org/forums/showthread.php?t=26777). Also her price is little bit high, you can get these boards for a little bit cheaper (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=110063272907) if you have the patience.
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Actually, I have a 3640 here which I intended to put in there but this guy too uses the onboard RAM.
But then again, that depends if I resolve my kickstart problem.
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@eslapion
Hi
I have this same problem and i have been searching for ZIP's to, if you come to any conclusions please inform me
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Hi Everybody,
I saw Softhut still lists Page and Static mode
ZIP Rams for $5 and $4 each. I do not know
if they really have them on stock, but can't
hurt to ask them. :-) Link: http://www.softhut.com
Of course obtaining a turbo card and using
simms should give you more ram and better
performance.
Regards,
Tamas
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I just ordered zips from softhut a couple months ago, and I got them within days..
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Cool i have to write them a mail. :-)
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The easy solution: buy ZIPs at ebay, Softhut, ...
The cheap solution with a moderate amount of work: build a PS/2 SIMM adapter that fits on top of the ZIP sockets and load that with 4/8 MB SIMMs. The PCB & sockets are <$10, SIMMs are free and work ~1 day. With an A3640 CPU board there's no sense fitting static column chips as it can't burst anyway.
The adapters you were looking at will most likely not fit, as countzero pointed out. The amount of work is ridiculous and the material still pricey.
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Zac67 wrote:
The easy solution: buy ZIPs at ebay, Softhut, ...
The cheap solution with a moderate amount of work: build a PS/2 SIMM adapter that fits on top of the ZIP sockets and load that with 4/8 MB SIMMs. The PCB & sockets are <$10, SIMMs are free and work ~1 day. With an A3640 CPU board there's no sense fitting static column chips as it can't burst anyway.
The adapters you were looking at will most likely not fit, as countzero pointed out. The amount of work is ridiculous and the material still pricey.
The "problem" with software hut's pricing... if it is a problem... is Static column chips are actually cheaper than slower page mode chips. But then again, the ZIP adapters are the same price... 4$ each.
Being an electrical engineer, I know for a fact that soldering SOJ chips on the ZIP adapters represent a LOT less work and is a LOT more reliable than trying to put a SIMM adapter on top of the ZIP sockets. Just a bit of syringe solder paste and a quick pass of a small butane torch and its done. Also, if the ZIP adapters don't fit then neither do the real ZIPs... check the size of the adapters in the specs!
To put a 72 SIMM adapter on top of the ZIP sockets you have to know exactly what ZIP socket matches with what bank in the 3000, otherwise you could cause some serious short circuit. A SIMM uses the same address and CAS/RAS lines for all the chips on it and the 3000 has 4 independent 4 MB banks that must be matched together.
I know the good old Amifast did that but I have no schematics for that device.
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The SOJ chips are already a bit thicker than ZIPs. According to the data sheet, the adapter adds 1.27 mm to that and I highly doubt that they do fit - although I'd have to measure the spacing to be sure.
Of course you have to know, which line is where:
(http://wowohl.de/Pix/A3000_16B-FastMem.png)
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yeaa... all that mess makes me glad the stuff i work with uses sram
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Oh btw: if you can't get a hold on PS/2 SIMM sockets: just solder short pieces of wire to the contacts and use them as SIPs - quickly done and works great.
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Zac67 wrote:
Oh btw: if you can't get a hold on PS/2 SIMM sockets: just solder short pieces of wire to the contacts and use them as SIPs - quickly done and works great.
I looked at the pinout of 72 PIN SIMMs and it seems to be like 4 30 pin SIMMs packaged on one board.
However, as the 3000 treats banks of 4MB as a single unit having 1 million cells of 32bits each, it has a single RAS/CAS set of lines. A 72 pin SIMM has 4 of these.
I suppose, in theory you could use a single 16MByte SIMM to fill the max RAM capacity of a 3000 but it seems to me that would require shorting together address lines that truly weren't supposed to be shorted together.
Even using 4MB or 8MB SIMMs causes me a real headache. Do I simply connect all 4 CAS/RAS lines from the SIMM to the single CAS/RAS set coming from the 3000 ?
The only type of SIMM I would feel pretty confident plugging into the ZIP sockets is the 30 pin type. The pins functions of a 1MB 30 pin SIMM, apart from the unused parity related lines, are the same as a ZIP chip except it has 8 data lines instead of 4.
If you have any plans to help plugging a 72 pin SIMM to a 3000 then I would love to see it.
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I have a question about A3000 Fast Ram.
Below the ZIP slots, are sockets for DIP style memory chips, that if filled, will get you up to 16megs. Has anyone ever found any of those or have they dissapeared off the face of the earth?
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The DIP sockets are only good for 1MB, and can't be used in conjunction with ZIP RAM. The stock 2MB configuration had 1MB of chip, 1MB of (DIP) fast. When you updated the fast, you could move the 1MB DIP chips to the chip ram.
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adolescent wrote:
The DIP sockets are only good for 1MB, and can't be used in conjunction with ZIP RAM. The stock 2MB configuration had 1MB of chip, 1MB of (DIP) fast. When you updated the fast, you could move the 1MB DIP chips to the chip ram.
WRONG!
As long as you put the same type of chip in the ZIP and DIP sockets, you CAN have chip in both type of sockets. As a matter of fact, you will notice that some ZIP sockets have the same UXX numbers as the DIP sockets. That's because they are connected together.
DIP sockets on the fast RAM of the MoBo can accept both 256x4 or 1Mbitx4 chips and fast page mode DRAM chips of both capacities exist in both ZIP and DIP packages.
As long as you don't populate both sockets having the same number and you use the same types of chips, you're okay.
I know so... I did exactly that in my first A3000 15 years ago. It's first 4MByte was 8 1Mbitx4 DIP chips and the last 12MBytes were ZIPs. I did this because DIPs were cheaper than ZIPs.
So, to answer Amiduffer's question: There are 32 ZIP sockets in the 3000's fast RAM section AND 8 DIP sockets. The 8 DIP sockets are just "clones" or "reconnected versions" of the 8 first ZIP sockets. So, if you want 16Mbytes in a 3000, you can either have 32 ZIP chips of 1Mbitx4 or 8 DIP chips of 1Mbitx4 and 24 ZIP chips of the same capacity. Just make sure the part number on your DIP and ZIP chips are the same.
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@eslapion
Take a look at the schematics: there are four CAS and four RAS lines to address the four RAM banks (1 MB or 4 MB each). With PS/2 SIMMs you can either use 4 sockets (one bank each/4 MB SIMMs) or 2 sockets (two banks each/8 MB SIMMs). The latter are even more common and need less soldering.
I think the DIP sockets will only take 256x4 chips, so you're stuck with 256x4 ZIPs, too. No point having 4 MB total.
Are you sure those take 1Mx4, too?
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Zac67 wrote:
I think the DIP sockets will only take 256x4 chips, so you're stuck with 256x4 ZIPs, too. No point having 4 MB total.
Are you sure those take 1Mx4, too?
I am absolutely sure! Back then I put chips no. 514400 (by Hitachi, Hyundai, Motorola or OKI) in my 3000. This chip exist in DIP, ZIP or... SOJ packages. And SOJ chips are used on SIMMs.
See: http://www.infinityelectronics.com/crossref.htm
I have a HEAP of 30 pin SIMMs here with the SOJ version of this chip on them. That's why I was interested in buying SOJ to ZIP adapters in the first place. Turns out the adapters are the same price as the ZIPs themselves...
Also, if you look at the cross-reference, it turns out there are many other companies making totally equivalent chips with different numbers. Mitsubishi and TI use number 44400 which I also saw very often on many 30 pin and 72 pin SIMMs too. Not to be outdone, Samsung's 44C1000 is also a frequent find.
All of them 1Mbitx4 chips, all of them fast page mode perfectly compatible with the 3000... if only I could connect them properly...
Take a look at this datasheet: http://www.alldatasheet.com/datasheet-pdf/pdf/31681/TOSHIBA/TC514400AAZ-60.html
Now see how the DIP and SOJ pinout are just about identical.
If anybody has an Amifast or SIMMfonie for sale... I sure would like to make copies of it.
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WRONG!
As long as you put the same type of chip in the ZIP and DIP sockets, you CAN have chip in both type of sockets. As a matter of fact, you will notice that some ZIP sockets have the same UXX numbers as the DIP sockets. That's because they are connected together.
DIP sockets on the fast RAM of the MoBo can accept both 256x4 or 1Mbitx4 chips and fast page mode DRAM chips of both capacities exist in both ZIP and DIP packages.
As long as you don't populate both sockets having the same number and you use the same types of chips, you're okay.
I know so... I did exactly that in my first A3000 15 years ago. It's first 4MByte was 8 1Mbitx4 DIP chips and the last 12MBytes were ZIPs. I did this because DIPs were cheaper than ZIPs.
So, to answer Amiduffer's question: There are 32 ZIP sockets in the 3000's fast RAM section AND 8 DIP sockets. The 8 DIP sockets are just "clones" or "reconnected versions" of the 8 first ZIP sockets. So, if you want 16Mbytes in a 3000, you can either have 32 ZIP chips of 1Mbitx4 or 8 DIP chips of 1Mbitx4 and 24 ZIP chips of the same capacity. Just make sure the part number on your DIP and ZIP chips are the same.
Cool. Too bad DIP memory chips are harder to find than ZIPs.
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Hi guys!!!
I have 16 mb ZIF for A3000! But not use!
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Looking at the pinout, you're completely right - didn't know that yet!
I'm still looking for 8pcs 1Mx4 static column (514402) - just to replace the one bank FP for completeness. ;-)
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Software Hut says they have them... 4$ apiece.
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I have found adapters A325-ND on Digikey.com that would technically allow you to put DRAM chips 514400 in SOJ format from SIMMs in DIP sockets.
However, the price of these is also quite high and in the case of the 3000, since only the first 8 sockets are connected between DIP and ZIP, that would limit to a max of 4MB... :-(
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@eslapion
I stand corrected, but at least I was correct about not being able to get 16MB out of DIPs. (I always assumed that 1Mbx4 DIPS were not usable...).
I have a AmiFAST for sale. How much you got?