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!

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.

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

Cool i have to write them a mail.  :-)

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.

yeaa... all that mess makes me glad the stuff i work with uses sram

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.

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.