A3000 Chip RAM Question

[bertambala]

Hello everyone,

Can anyone here tell me if the following would work for chip ram in an A3000D?  I've got 1MB, and would like to bump it up to 2.
Arcade Components

As far as I can tell, yes, but I'd rather be sure.  If not, there are a few other 44256 DRAM DIPs listed here: Arcade Components

I apologize if this is a duplicate, but I wasn't able to find anything conclusive by searching the forums.  Thanks in advance!

[Tenacious]

I don't know if the ram you linked to is compatible.  

I'm curious how you acquired an A3000D with only 1 Meg of chip.  IIRC, the A3000 originally shipped with 1 meg of chip AND 1 meg of fast.  The chips in the fast ram sockets could be moved to the remaining empty chip ram sockets.  The fast ram sockets could then be populated with higher density zip chips (upto 16 megs).  

The point is, most A3000s had those chips swapped to chip memory sockets years ago.  How is your A3000 configured?

[joekster]

That is the right chip, but the wrong speed. My A3000 came with 100ns ram - I wouldn't want to put anything slower in it. Try the "44256-6 DRAM", its the same price - but twice as fast. I would reccomend getting an old ISA video card from ebay, it will give you all 8 chips for the price of 1 from the link you gave.

[AMC258]

My A3000UX came with 1M of Chip RAM and no, the other 1M was not in the Fast RAM sockets.  In fact, there was a note from Commodore about how you could buy an additional 1M.  There was 4M of Fast RAM in the form of ZIPs installed.

I sacrificed and took 1M of Chip RAM out of two of my A3000s so I could put 2M Fast RAM in my A2000.  I think one A3000 still only has 1M.  The A2000 is collecting dust because all it can do these days is crash intermittently.  All my A2000s have suffered this fate at some point.

[konishipol]

The RAM for A3000 CHIP ram can often be found on old graphics card for PC's (from the early 90's) - these can generally be found on the street. But also lots of other Amiga machines use the same type of memory, also most FAST RAM expansion cards for Amiga 500 which can be a cheap way of getting hold of these chips...

Most A3000 came with 1mb CHIP RAM and 1mb FAST RAM, which could be turned into CHIP RAM by moving the chips.

I don't think you'll have much problem finding more RAM chips to fill the remaining 1mb, but I wish you good luck anyway Let us know what you find!

[rkauer]

Intermittent issues in an A2000 are commonly caused by a bad PSU!

[AMC258]

Usually, but not always.  The first one was the power supply.  So, I put in a new power supply.  After that, OS1.3 would work fine but 2.04 would lock on booting.  So, I replaced the motherboard.  It worked for about two weeks, then it started getting intermittent.  So, I put in another motherboard (yes, I do have a large stack of them), and a power supply just in case.  That one worked for a while, but now it fries CIA chips often.  The current one runs just fine until the first time I StartToaster, then it just gets plain intermittent.  The P/S is good.  If I wipe out everything and install it from scratch, it will work just fine until the first day I StartToaster.  And, this is with several Toasters, several Flyers, any combination of Zorro cards, multiple accelerators, different versions of Toaster software, different OS versions, different RAM.
Assuming the case is posessed, I bought yet another A2000 with more memory and a better accelerator almost exactly a year ago.  I have yet to plug it in.  So, now not only can I not make the time to do some serious diagnostic work and fix one A2000, I don't have the time to power on another one!

[bertambala]

Thank you for the help and advice everyone!

Tenacious: I got this 3000 second-hand back in the summer of '91 (upgrading from a 500), and it came with 1 MB of Chip and 4MB of Fast (perhaps 3, but I think it is 4).  It has a factory sticker on the back listing the specs (25MHz, 100MB HDD, RAM specs), so I'm pretty sure it was a default configuration.  Other than upgrading to 3.1 in '98 I've kept her stock, but that's about to change.

joekster: Thanks for the info!  I found a Japanese site that listed the RAM as being 120ns (Japanese Amiga Site) , but if it is indeed 100 I will buy that.  As for the ISA graphics cards, are there any particular brands or models to look for?  Or are they all pretty much populated with the right kind of chips?

konishipol:  That's also very good to know, I'll check on 500 RAM expansions as well.  I knew that the zips were hard to come by, so I'm relieved to know it's not the same case for the dips!

[TjLaZer]

I went to my local PC junk store and bought a bunch of old ISA video cards with chips that looked the same as the ones in Amigas (I was upgrading some A2091 cards to 2MB as well as a A600 1MB card)  I got lucky they all worked.  I would count the pins and just see if you can find some old cards and just try them.  Try to get faster chips though if you can.

As noted above, some A3000's shipped with 1MByte of FAST memory in DIP package, waiting to be transplanted into the sockets for CHIP RAM, once more FAST RAM was installed. Those FAST memory sockets are the U850D-U857D 20 pin DIP places, Bank 0. This bank is electrically mapped to Bank 0 U850-U857, 20 pin ZIP sockets. As a result, one can make a three megabyte A3000 configuration by putting 256Kbit x 4 chips into the FAST RAM DIP sockets without buying ZIPs. Or a six meg setup, using 1MBit x 4 chips. The DIP FAST sockets cannot be used with the ZIP sockets all together, as the two Bank 0 areas are basically pinned to each other (as noted by the same component numbers, one set with a D for DIP). One could have 4MBytes of DIPs for FAST, then another 12MBytes of FAST in ZIPs placed into Banks 1-3, but not 4MBytes in the DIP area and 16MBytes in all four ZIP banks.

I did not know you could add 4MB of DIPS to the A3000!  That is great to know.  A 6MB A3000 using cheap DIPS would not be a bad thing...

[Zac67]

You can even mix DIPs and ZIPs: the DIPs replace the first bank of ZIPs, so their sockets must stay empty. They all have to be the same density (4x1M = 514400 or 514402), of course and AFAIK static column DIPs don't exist on this planet.