A2000 4.0 motherboard, memory card expansion the wrong way around.

[Turran]

I have a very old amiga 2000 v4.0, german creation, before it moved to the US.

It came with this goodie:
http://www.amiga-hardware.com/showha...cgi?HARDID=967

512kb fastram for the CPU slot. Only works in this particular 4.0 amiga.

Anyway, I bought another 512kb and stuck in there without problems. When it came to putting the card back I was tired and put it in the wrong way.

I got a yellow screen of course. Saw what the problem was so I turned it around, but now I only get a yellow screen, even after taking the memory out again.

What happens when you insert a card the wrong way around? I cant see anything burned on it atleast and would very much like to save the old beauty.

Works fine without the card in, I should add.

Thanks

[mark_k]

Oh dear. Best case scenario, one of the RAM chips you added is bad hence the Kickstart memory test fails. But more likely, inserting the card the wrong way around damaged one or more chips on the RAM board. I don't know the CPU slot pinout from memory, but if instead of +5V and 0V on the relevant pins you had 0V and +5V with the card inserted incorrectly, that would not do the chips any good.

If you want to risk damaging your motherboard, you could try putting the RAM card back in, and see if any of the chips get very hot.

[roy bates]

youve probably killed some of the baords logic.the socket carrys +5,-5 and +12 volts.
so any and all of these voltges would/could easily be passed to the data path.

im not saying its beyond repair,just difficult.

[Turran]

Hrmp. Ok, thanks. I just bought a 2MB zorro board for it instead. Guess it goes in the bin.

[mark_k]

Out of interest I looked up the CPU slot pinout in the A500/A2000 Technical Reference Manual. Two of the most damaging things from inserting the card the wrong way around would have been:
slot pin 8 (-5V) to card pin 79 (D2 data bus line)
slot pin 10 (+12V) to card pin 77 (D1 data bus line)

If you can find another card cheaply, get that and be careful when you install it. The extra RAM is useful because it should be faster than chip RAM and you'll have more chip RAM free. (Compared to Zorro II RAM + chip RAM only, where Kickstart puts some things in Chip RAM.) Plus some old games/demos require $C00000 RAM.

If you'll otherwise be throwing the broken card away, could you send it to me instead? I want to figure out the jumper settings on the card. Apparently it's possible to configure the RAM as Kickstart RAM, or maybe $F00000 RAM. There may be the possibility of loading a later/custom Kickstart into the RAM. I could trace where the jumper pins go to try to figure out all the possible settings.

[roy bates]

Originally Posted by mark_k

Out of interest I looked up the CPU slot pinout in the A500/A2000 Technical Reference Manual. Two of the most damaging things from inserting the card the wrong way around would have been:
slot pin 8 (-5V) to card pin 79 (D2 data bus line)
slot pin 10 (+12V) to card pin 77 (D1 data bus line)

If you can find another card cheaply, get that and be careful when you install it. The extra RAM is useful because it should be faster than chip RAM and you'll have more chip RAM free. (Compared to Zorro II RAM + chip RAM only, where Kickstart puts some things in Chip RAM.) Plus some old games/demos require $C00000 RAM.

If you'll otherwise be throwing the broken card away, could you send it to me instead? I want to figure out the jumper settings on the card. Apparently it's possible to configure the RAM as Kickstart RAM, or maybe $F00000 RAM. There may be the possibility of loading a later/custom Kickstart into the RAM. I could trace where the jumper pins go to try to figure out all the possible settings.

spot on,you could try to replace the defuct logic to get it working again.
the 74 series logic cant be that expensive to obtain,i dont know about the drams though.

is there any truth to this card only working on a revision 4 board?

[mark_k]

Originally Posted by roy bates

spot on,you could try to replace the defuct logic to get it working again.
the 74 series logic cant be that expensive to obtain,i dont know about the drams though.

is there any truth to this card only working on a revision 4 board?

There are also three PALs on the board. Replacing those, if they are faulty, could be trickier. The big problem would be figuring out exactly which chips have been damaged.

Apparently that card does only work on German A2000 boards. However, at the time the earlier B2000 models had 512KB of $C00000 RAM on the motherboard. So there would be a clash between RAM on the card and the motherboard RAM. Whether it would work with a B2000 board which has ECS Agnus and 1MB chip RAM is another question. (My guess would be it probably doesn't, but someone would have to try it.)

Also, the address of the RAM board memory can be changed to maybe $F00000 or $F80000 (I'm not sure). It might have more chance of working at that address in a B2000.

[roy bates]

Originally Posted by mark_k

There are also three PALs on the board. Replacing those, if they are faulty, could be trickier. The big problem would be figuring out exactly which chips have been damaged.

Apparently that card does only work on German A2000 boards. However, at the time the earlier B2000 models had 512KB of $C00000 RAM on the motherboard. So there would be a clash between RAM on the card and the motherboard RAM. Whether it would work with a B2000 board which has ECS Agnus and 1MB chip RAM is another question. (My guess would be it probably doesn't, but someone would have to try it.)

Also, the address of the RAM board memory can be changed to maybe $F00000 or $F80000 (I'm not sure). It might have more chance of working at that address in a B2000.

yep,the pals would be very tricky.but if you had the card it could be traced to wherever the power was applied.

on the subject of whether it would work in later model,
i would be interested to see if it could work,but im not over confident.

[tesla]

Note to Turran;

Many times, when power is mis-applied to a board, chips will short out internally, crack, be discolored or melted, or even "blow" which means the top, or parts of the top blow off. In this case you will in many cases, actually be able to see the silicon chip, Don't ask me how I know :P

BTW, why did they design the board so it could be inserted wrong?

[roy bates]

many a person has fallen for this inserted card the wrong way,ive seen it on ide and sound cards all where half size(i'll admit ive only seen it happen on zorro cards)

[Turran]

Hehe could be.

I actually bought this Amiga to pimp it up, not knowing that it was a 4.0 motherboard, thus not really useful for pimping. Would you be interested in the whole thing Mark_K? Otherwise, PM your address and you can have the ram card for free.