YES I finaly got it solved, the 3.1 Rom's are working in my 3000!!! :-) :-) :-)
After seeing the pictures Crusher posted with the 3.1 rom reversed in the socket while i also could see he had the same Rev. (7.x) mainboard with exacly the same Rev Rom-tower i got really confused. Could it be possible that my (until now not working) 3.1 Roms should be installed reversed in their sockets? Even If the original roms (V1.4 bootroms) AND the kickstart 3.1 Roms taken from my A1200 worked correct without reversing? I wanted to know for sure and took the schematics of the A3000 and compared them with the schematics of the A4000 and i also found out what the rom-tower is doing by measuring the lines from the sockets where the roms go to the pins which go into the rom-sockets on the amiga.
[color=0000ff]This is what the rom-tower is doing (short version):[/color]
Sockets U180 & U181 on the A3000 have Adresslines A2...A18 from the amiga go to A1...A17 on the rom chips.
Sockets U180 & U181 on the ROM-Tower have the same Adresslines A2...A18 coming from the amiga go to A0...A16 on the rom chips.
The A4000 and A1200 also have A2...A18 go to A0...A16 on the roms and that is where they are supposed to be. So basicly that is what the romtower is correcting, all other signals (D0..D15/D31, OE, CS, GND,VCC) stay the same.
So this confirms that the kickstart roms (wheter they are KS2.x or 3.x) should be placed in the same position as the original bootroms have been.
Still i did not have my KS3.1 at work and i also found out why: The Adresslines of A4000 and i guess also newer models of A3000 (Rev 8.x an higher) decode also A19 (from amiga) to A17 (on rom chip) which makes for a total of 1024K of rom space (18 adress lines, 16 data lines, 2 chips = 2^18x2(bytes)x2(chips)=1024Kbytes). On older Rev. (6.x, 7.x) A3000 A19 is not connected and that leaves room for max 512Kb. So since KS3.1 is (only) 512kb it should work great right? But my KS3.1 did not work. Looking a bit closer at my KS3.1 (they are eproms and not roms in my case) i found out that my chips are 4mbit (512kb) each so that totals to 1024K so that means only half of it it filled with the KS3.1 code and the other half is not used. Now how does the amiga select the 'right' part of the chip and not the part which is not used? It uses the extra adresline (Amiga A19, Rom A17) to do so! I think this extra line was intended for future kickstarts which might be bigger than 512K (Older KS1.2/1.3 was only 256K and grew to 512 starting with KS2.0). The A17(rom) line on the sockets on the ROM-Tower was not connected to A19 (amiga) but was connected to ground(0V) and with that it selected the unused part of my Eproms and that is why my KS3.1 did not work in my Amiga3000. Until now because after i reconnected the A17 lines from my eproms to +5V (which makes the amiga use the other half of my eproms) it finaly worked :-D :-D :-D
So this also explains why 'some' KS3.1 roms seem incompatible with A3000 with rom Tower. Some roms like my eproms are actualy twice the normal size and need A17 attached to +5V to select the part where the code is. The 'compatible' roms probably are the right size and have no A17 so they would work in the rom-tower where the A17 line is connected to ground. (Ofcourse if the code in my rom would have been in the other half they would have worked too but would then be incompatible in newer rev's A3000 with A19 from amiga attached to A17 from rom).
It's a long story but it took me some time to find out how it all connected and i hope that this can help others who have the same problem if they try to install Kickstart 3.1.
Also i would like to thank all of you who posted (again :-) ) because without the postings i would not have searched so long i guess.
Tom
