2nd hand A4000 does not show Fast Mem. How come ?

[Effy]

I have an A4000 desktop here (one of three) with an original 68030 and superbuster 9 and a battery that looks not like a disaster. I don´t see any traces of acid on the board, though the battery itself has some corrosion (?) on it but this can be removed by using a strong toothbrush.
When I tried it it refused to boot up, giving a green screen and once in a while blink and then gave again a green screen.
So I opened it up and saw the problem : no Ram. So I searched in my cigar-box with Ram modules and after trying a few times the A4000 finally booted up giving 2 Mb Chip. Cool !! But the problem started at this point when I tried to add Fast Ram. This is until now still not recognized. I use modules of 4 Mb and 8 Mb, one at a time and this at every place I can put a module in (4). The modules itself can not be faulty, not all of them. So what am I doing wrong There is no harddrive connected, only floppy, and it does boot up from that one ... there is also no Zorro card inside  ... have I forgotten something

[Effy]

Is this one of those "things in life that can happen" Does this mean that the only way to add Fast Ram is a turboboard or a FastLane scsi controller I do have got a FastLane (from Ebay) but I haven´t tried it yet ... and I have no turboboard ...  

[Morley]

Well, there should be a jumper to choose between 1/2 MB simms and 4/8 MB simms. The Chip simm should be 2 MB. If you are using 8 MB simms only alternate positins could be used, to a total of 16 MB.

[SilvrDrgn]

Get rid of that battery off of the motherboard as soon as possible!  No matter how much cleaning you do, it won't be enough.  Replace it with a Lithium coin batter any a diode (to prevent charging).  Or hook wires up in the battery's place and mount a new one somewhere else off of the motherboard (that's what I did).

[Ilwrath]

Yep.  The CHIP ram needs to be a 2MB simm in Bank 0.  The Fast RAM should be in banks 1 and 3 if you are using double-sided simms, or in banks 1,2,3,4, if you are using single-sided simms.  And I do believe there is a jumper to set for the 1/2 or 4/8 SIMM sizing.  And, most likely, single-sided 8MB SIMMs, or double-sided 4MB SIMMs aren't compatible, and will be detected wrong.

I think that was the lessons I learned on A4000 RAM setup.  ;-)

Warren Block's A4000 hardware page is an excellent source of knowledge.

[Effy]

I have tried several Simms, 4 Mb,8 MB,16 MB, and this in bank 1 to 4, which means I had to do a lot of replacing. None of them works, only the chip mem works and this turns out to be 2 Mb when I get into the workbench...

[Effy]

Did some more experimenting. It turned out that the module for chip ram was a 16 Mb or 32 Mb, so I decided to replace it by a smaller one because after all only 2 Mb will be used. So I tried some modules that looked like 4 Mb or 8 Mb. Turned out I got only 1 Mb or even 512 K Chip Mem !!! Totally uncool !!! Continued to experiment with other modules and after using a very small module that didn´t seem to have many chips on it, I got my 2 Mb Chip Mem back.
Then I continued to get the Fast Ram to work, but no results. At this moment I have in bank 1 and 2 two identical modules that may be 4 Mb maximum. Now two jumper settings:
-jumper 214 : set to VBB and not to 1 8M
 placed to the upper left of the buster chip
-jumper 852 : set to 256Kx32 and not to 1x32
 placed almost under the daughterboard close to chip mem module
My A4000 has a motherboard Rev B

Any cool advice would be very welcome, especially because of the burning sun outside ...

[Morley]

Any cool advice would be very welcome, especially because of the burning sun outside ...

Grab a crate of beer and get out, drink your troubles away if necessary. Wait till next rainyday with your memory-woes.

[Ilwrath]

Yes, I believe you should use exactly a 2MB simm for your chip RAM.  Others may work, but return unexpected results.  I have heard that this has to do with various sized SIMMs using different internal addressing systems.  The Amiga is expecting a single-sided 2MB SIMM in bank 0.  Anything else is a crapshoot as to what will happen.

-jumper 852 : set to 256Kx32 and not to 1x32

This should be set to 1x32.  That allows 4MB and larger simms.
(After all a 4MB SIMMs is 1MBx32bit.)  ;-)

[Effy]

Morley : I am already trying to do the job with italian red wine ... :-)

Ilwrath : so it could be that the not-2Mb-chip in the chip mem bank causes the other memory banks not to work  :-?  

[Ilwrath]

so it could be that the not-2Mb-chip in the chip mem bank causes the other memory banks not to work

I don't know.  I've never tried anything other than a 2MB SIMM.  I don't *THINK* it should interfere with other RAM, but I'm not sure.  More likely, I'd think it would just result in mis-detected CHIP RAM size (which you've had) or corruption and errors in CHIP RAM, causing gurus, unbootable, etc.

But, for sure, the 1x32 jumper should be set, to use any SIMM larger than a 2MB in fast RAM.  Also, the SIMMs used in fast RAM should all be the same size and style.  (in other words, don't use a 4MB and a 8MB together, and don't mix single- and double-sided SIMMs.)  I always keep the same speed and manufacturer on all SIMMs, as well, but probably not necessary.

[Effy]

At the moment those three Simm´s that are placed are all three single sided and probably not bigger than 4 Mb each ... but I shall check on that jumper ...

[TjLaZer]

Sounds like you have some traces bad.  I had a leaky batt in my 4000 and it was very minor but the RTC was dead due to some traces corroded, but RAM is ok.  Since the SIMM slots are real close to the batt this may be the case for you.  Good luck.

[Effy]

The pitty side of this A4000 is that is has got superbuster 11 and kick 3.1 ... but maybe I can transfer an 68040/25 from another A4000 to this one and use this when I get it :
X-calibur ... which will allow me to use up to 4x32 Mb Simm´s !! That way there will be no ´slow´ fast memory on the motherboard that may slow the system down  :-)

[Acill]

The first thing you need to do is get an A4000 COMPATABLE 2MB simm for the chip RAM. I would say its that RAM you have causing the trouble. Call a few shops and see what they have. I bet you can get one thats good for the system.