A2000 Rev.6 Only 512kb showing up

[Tatsu]

I should have 1MB in total and i want all to be chip offcorse. I tried diffrent jumper settings and swithed some chips with an old A500 to no vail.
But when I set J101 and J500 to have 1MB, the computer does not boot. With kick 2.04 the screen flashes with some lines with different colours. With kick 1.3 the screen stays gray but the power lamp flashes continuosly. Reseting does nothing.
Gary is 8372A and i have tried a newer revision also, no change.
But the other 512kb that should show up as "other" or "fast" mem is not showing up at all either. Could some memory chips be broken? I have 8 pieces of MB81C4256-10p I am not sure they add up to 1MB but they should when I have Rev6 I believe.

[save2600]

do you have the right Agnus chip in there? Even if you do (8372), there may be another jumper that needs to be made. I had the same problem relatively recently on a 2000 refurb. The thread is here, somewhere - but the jumper I am talking about only has its solder pads - NOT a traditional pin and removable jumper scenario. If you don't get this figured out, I'll take a look at my spare A2000 mobo hanging on the wall and identify what solder pads I am talking about and report back. At work now is the thing. In the meantime, if you want to look for yourself - look for some tiny square pads (3 of 'em) near Agnus. If this is the problem, you simply cut the one trace and solder a connection to the other starting from the middle pad. 'Course, I could be totally wrong and getting my mobo revisions mixed up. I see Mechy is on the spot to help save the day...  lmao

Very unlikely you've got bad RAM chips as most of the time, it'll show full RAM available, but yield strange problems as it fills up.

[Tatsu]

Thanks for replying. I meant offcourse agnus, not gary. I will hunt for theese pads then.
I see no other memory then 512kb chip, if i have not made myself clear on that subject. I have a strange 1MB commodore card wich fit in the cpu/mmu-slot it shows as 512kb fast. But i cant seem to make that either to be chip mem, but that could very likely be impossible also.

[save2600]

That Fast Slot memory card... wasn't that just for use with the really early German made A2000's? Yeah, you're not going to get that puppy configured as Chip RAM I bet, so don't pull your hair out trying. I'd concentrate on seeing what's up with your mobo jumper settings and Agnus version. 8371 and lower revisions only allow 512kb Chip IIRC.

Regarding the Fast Slot memory card... there may be some conflict there too. How does the computer behave with it out? Personally, I'd ditch that thing considering your revision mobo and seek a regular Zorro II Ram solution - they're certainly cheap enough.

[Tatsu]

No, i am not using the ram-card normally, just tested it in a vague hope it really could be used as chip ram. Normally i have 8mb fast mem on my trump card anyway so i really have not noticed i was lacking half the memory of the mobo. I just now decided I wanted the other half MB to be chip mem. But it is nowhere to be found.
I found a open jumper J102 near agnus. But it probably just sets it for ntsc, and it has only 2 pads anyway. I will search some more.

[Tatsu]

I closed J102 but it did no difference at all. I am starting to think something is broken on the motherboard.
J101 can be in any position when J500 is open. But when J500 is closed only one position is possible on J101, the other shows the symptoms i allready told. I have switched Gary, Agnus and denise with an A500 but nothing helps. Its strange there is no problem when the extra 512kb is set for fastmem, other than that it doesnt show up. The computer is rock stable in that configuration.

[save2600]

I swear I had the same problem as you... thought something was broken, but it wasn't. Just needed the correct combination of jumpers settings, as goofy as it may seem (even if it conflicts with what the sites say they should do).  

What happens when you switch J900 by Gary? I can't seem to find any docs that tell us what that's for. J200 is to enable light pens, so no need to bugger with that.

J101, J102 and J500 - I'm thinking you gotta figure out the right combo there and yeah... searching on the site, finally found my A2000 1MB Chip conundrum:

http://www.amiga.org/forums/showthread.php?t=54211

[Tatsu]

No progress. J101, j500, j900, j206 nothing changes the status of the memory in any configuration. Exept maybe J101 in 2-3, and J500 closed. Then the computer refuses to start at all.
But in Your link You claim to at least have the extra 512kb visible. I can only see 512kb chip, nothing more what so ever. It is like the extra 512kb is not detected at all. In showconfig only 0,5MEG chip at $400-$7ffff is showing, nothing else. All of the eight memory chips has the same voltage to them at least, about 4.4 volt. I am not sure wich component(s) should tell the system of the existing memory.